Import SamplingProfiler from http://code.google.com/p/dalvik/

cp ~/android/dalvik/profiler/src/main/java/dalvik/profiler/* ~/android/master/libcore/dalvik/src/main/java/dalvik/system/profiler/
cp ~/android/dalvik/profiler/src/test/java/dalvik/profiler/* ~/android/master/libcore/dalvik/src/test/java/dalvik/system/profiler/
perl -p -i -e 's/package dalvik.profiler;/package dalvik.system.profiler;/' ~/android/master/libcore/dalvik/src/*/java/dalvik/system/profiler/*.java
perl -p -i -e 's/import dalvik.profiler./import dalvik.system.profiler./' ~/android/master/libcore/dalvik/src/*/java/dalvik/system/profiler/*.java

Change-Id: Iae3f63327f4a9dde7f037e69c22057e2ea704aaa

11 files changed, 1936 insertions, 1741 deletions

diff --git a/dalvik/src/main/java/dalvik/system/SamplingProfiler.java b/dalvik/src/main/java/dalvik/system/SamplingProfiler.java
deleted file mode 100644
index b2ee6fb..0000000
--- a/dalvik/src/main/java/dalvik/system/SamplingProfiler.java
+++ /dev/null
@@ -1,1728 +0,0 @@
-/*
- * Copyright (C) 2010 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package dalvik.system;
-
-import java.io.BufferedInputStream;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.EOFException;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.io.PrintWriter;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.Comparator;
-import java.util.Date;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map.Entry;
-import java.util.Map;
-import java.util.Set;
-import java.util.Timer;
-import java.util.TimerTask;
-import libcore.util.Objects;
-import libcore.io.IoUtils;
-
-/**
- * A sampling profiler. It currently is implemented without any
- * virtual machine support, relying solely on {@code
- * Thread.getStackTrace} to collect samples. As such, the overhead is
- * higher than a native approach and it does not provide insight into
- * where time is spent within native code, but it can still provide
- * useful insight into where a program is spending time.
- *
- * <h3>Usage Example</h3>
- *
- * The following example shows how to use the {@code
- * SamplingProfiler}. It samples the current thread's stack to a depth
- * of 12 stack frame elements over two different measurement periods
- * with samples taken every 100 milliseconds. In then prints the
- * results in hprof format to the standard output.
- *
- * <pre> {@code
- * ThreadSet threadSet = SamplingProfiler.newArrayThreadSet(Thread.currentThread());
- * SamplingProfiler profiler = new SamplingProfiler(12, threadSet);
- * profiler.start(100);
- * // period of measurement
- * profiler.stop();
- * // period of non-measurement
- * profiler.start(100);
- * // another period of measurement
- * profiler.stop();
- * profiler.shutdown();
- * HprofWriter writer = new AsciiHprofWriter(profiler.getHprofData(), System.out);
- * writer.write();
- * }</pre>
- *
- * @hide
- */
-public final class SamplingProfiler {
-
-    /**
-     * Represents sampling profiler data. Can be converted to ASCII or
-     * binary hprof-style output using {@link AsciiHprofWriter} or
-     * {@link BinaryHprofWriter}.
-     * <p>
-     * The data includes:
-     * <ul>
-     * <li>the start time of the last sampling period
-     * <li>the history of thread start and end events
-     * <li>stack traces with frequency counts
-     * <ul>
-     */
-    public static final class HprofData {
-
-        public static enum ThreadEventType { START, END };
-
-        /**
-         * ThreadEvent represents thread creation and death events for
-         * reporting. It provides a record of the thread and thread group
-         * names for tying samples back to their source thread.
-         */
-        public static final class ThreadEvent {
-
-            public final ThreadEventType type;
-            public final int objectId;
-            public final int threadId;
-            public final String threadName;
-            public final String groupName;
-            public final String parentGroupName;
-
-            public static ThreadEvent start(int objectId, int threadId, String threadName,
-                                            String groupName, String parentGroupName) {
-                return new ThreadEvent(ThreadEventType.START, objectId, threadId,
-                                       threadName, groupName, parentGroupName);
-            }
-
-            public static ThreadEvent end(int threadId) {
-                return new ThreadEvent(ThreadEventType.END, threadId);
-            }
-
-            private ThreadEvent(ThreadEventType type, int objectId, int threadId,
-                                String threadName, String groupName, String parentGroupName) {
-                if (threadName == null) {
-                    throw new NullPointerException("threadName == null");
-                }
-                this.type = ThreadEventType.START;
-                this.objectId = objectId;
-                this.threadId = threadId;
-                this.threadName = threadName;
-                this.groupName = groupName;
-                this.parentGroupName = parentGroupName;
-            }
-
-            private ThreadEvent(ThreadEventType type, int threadId) {
-                this.type = ThreadEventType.END;
-                this.objectId = -1;
-                this.threadId = threadId;
-                this.threadName = null;
-                this.groupName = null;
-                this.parentGroupName = null;
-            }
-
-            @Override public int hashCode() {
-                int result = 17;
-                result = 31 * result + objectId;
-                result = 31 * result + threadId;
-                result = 31 * result + Objects.hashCode(threadName);
-                result = 31 * result + Objects.hashCode(groupName);
-                result = 31 * result + Objects.hashCode(parentGroupName);
-                return result;
-            }
-
-            @Override public boolean equals(Object o) {
-                if (!(o instanceof ThreadEvent)) {
-                    return false;
-                }
-                ThreadEvent event = (ThreadEvent) o;
-                return (this.type == event.type
-                        && this.objectId == event.objectId
-                        && this.threadId == event.threadId
-                        && Objects.equal(this.threadName, event.threadName)
-                        && Objects.equal(this.groupName, event.groupName)
-                        && Objects.equal(this.parentGroupName, event.parentGroupName));
-            }
-
-            @Override public String toString() {
-                switch (type) {
-                    case START:
-                        return String.format(
-                                "THREAD START (obj=%d, id = %d, name=\"%s\", group=\"%s\")",
-                                objectId, threadId, threadName, groupName);
-                    case END:
-                        return String.format("THREAD END (id = %d)", threadId);
-                }
-                throw new IllegalStateException(type.toString());
-            }
-        }
-
-        /**
-         * A unique stack trace for a specific thread.
-         */
-        public static final class StackTrace {
-
-            public final int stackTraceId;
-            private int threadId;
-            private StackTraceElement[] stackFrames;
-
-            private StackTrace() {
-                this.stackTraceId = -1;
-            }
-
-            public StackTrace(int stackTraceId, int threadId, StackTraceElement[] stackFrames) {
-                if (stackFrames == null) {
-                    throw new NullPointerException("stackFrames == null");
-                }
-                this.stackTraceId = stackTraceId;
-                this.threadId = threadId;
-                this.stackFrames = stackFrames;
-            }
-
-            public int getThreadId() {
-                return threadId;
-            }
-
-            public StackTraceElement[] getStackFrames() {
-                return stackFrames;
-            }
-
-            @Override public int hashCode() {
-                int result = 17;
-                result = 31 * result + threadId;
-                result = 31 * result + Arrays.hashCode(stackFrames);
-                return result;
-            }
-
-            @Override public boolean equals(Object o) {
-                if (!(o instanceof StackTrace)) {
-                    return false;
-                }
-                StackTrace s = (StackTrace) o;
-                return threadId == s.threadId && Arrays.equals(stackFrames, s.stackFrames);
-            }
-
-            @Override public String toString() {
-                StringBuilder frames = new StringBuilder();
-                if (stackFrames.length > 0) {
-                    frames.append('\n');
-                    for (StackTraceElement stackFrame : stackFrames) {
-                        frames.append("\t at ");
-                        frames.append(stackFrame);
-                        frames.append('\n');
-                    }
-                } else {
-                    frames.append("<empty>");
-                }
-                return "StackTrace[stackTraceId=" + stackTraceId
-                        + ", threadId=" + threadId
-                        + ", frames=" + frames + "]";
-
-            }
-        }
-
-        /**
-         * A read only container combining a stack trace with its frequency.
-         */
-        public static final class Sample {
-
-            public final StackTrace stackTrace;
-            public final int count;
-
-            private Sample(StackTrace stackTrace, int count) {
-                if (stackTrace == null) {
-                    throw new NullPointerException("stackTrace == null");
-                }
-                if (count < 0) {
-                    throw new IllegalArgumentException("count < 0:" + count);
-                }
-                this.stackTrace = stackTrace;
-                this.count = count;
-            }
-
-            @Override public int hashCode() {
-                int result = 17;
-                result = 31 * result + stackTrace.hashCode();
-                result = 31 * result + count;
-                return result;
-            }
-
-            @Override public boolean equals(Object o) {
-                Sample s = (Sample) o;
-                return stackTrace.equals(s.stackTrace) && count == s.count;
-            }
-
-            @Override public String toString() {
-                return "Sample[count=" + count + " " + stackTrace + "]";
-            }
-
-        }
-
-        /**
-         * Start of last sampling period.
-         */
-        private long startMillis;
-
-        /**
-         * CONTROL_SETTINGS flags
-         */
-        private int flags;
-
-        /**
-         * stack sampling depth
-         */
-        private int depth;
-
-        /**
-         * List of thread creation and death events.
-         */
-        private final List<ThreadEvent> threadHistory = new ArrayList<ThreadEvent>();
-
-        /**
-         * Map of thread id to a start ThreadEvent
-         */
-        private final Map<Integer, ThreadEvent> threadIdToThreadEvent
-                = new HashMap<Integer, ThreadEvent>();
-
-        /**
-         * Map of stack traces to a mutable sample count. The map is
-         * provided by the creator of the HprofData so only have
-         * mutable access to the int[] cells that contain the sample
-         * count. Only an unmodifiable iterator view is available to
-         * users of the HprofData.
-         */
-        private final Map<HprofData.StackTrace, int[]> stackTraces;
-
-        public HprofData(Map<StackTrace, int[]> stackTraces) {
-            if (stackTraces == null) {
-                throw new NullPointerException("stackTraces == null");
-            }
-            this.stackTraces = stackTraces;
-        }
-
-        /**
-         * The start time in milliseconds of the last profiling period.
-         */
-        public long getStartMillis() {
-            return startMillis;
-        }
-
-        /**
-         * Set the time for the start of the current sampling period.
-         */
-        public void setStartMillis(long startMillis) {
-            this.startMillis = startMillis;
-        }
-
-        /**
-         * Get the {@link ControlSettings} flags
-         */
-        public int getFlags() {
-            return flags;
-        }
-
-        /**
-         * Set the {@link ControlSettings} flags
-         */
-        public void setFlags(int flags) {
-            this.flags = flags;
-        }
-
-        /**
-         * Get the stack sampling depth
-         */
-        public int getDepth() {
-            return depth;
-        }
-
-        /**
-         * Set the stack sampling depth
-         */
-        public void setDepth(int depth) {
-            this.depth = depth;
-        }
-
-        /**
-         * Return an unmodifiable history of start and end thread events.
-         */
-        public List<ThreadEvent> getThreadHistory() {
-            return Collections.unmodifiableList(threadHistory);
-        }
-
-        /**
-         * Return a new set containing the current sample data.
-         */
-        public Set<Sample> getSamples() {
-            Set<Sample> samples = new HashSet<Sample>(stackTraces.size());
-            for (Entry<StackTrace, int[]> e : stackTraces.entrySet()) {
-                StackTrace stackTrace = e.getKey();
-                int countCell[] = e.getValue();
-                int count = countCell[0];
-                Sample sample = new Sample(stackTrace, count);
-                samples.add(sample);
-            }
-            return samples;
-        }
-
-        /**
-         * Record an event in the thread history.
-         */
-        public void addThreadEvent(ThreadEvent event) {
-            if (event == null) {
-                throw new NullPointerException("event == null");
-            }
-            ThreadEvent old = threadIdToThreadEvent.put(event.threadId, event);
-            switch (event.type) {
-                case START:
-                    if (old != null) {
-                        throw new IllegalArgumentException("ThreadEvent already registered for id "
-                                                           + event.threadId);
-                    }
-                    break;
-                case END:
-                    // Do not assert that the END_THREAD matches a
-                    // START_THREAD unless in strict mode. While thhis
-                    // hold true in the binary hprof BinaryHprofWriter
-                    // produces, it is not true of hprof files created
-                    // by the RI. However, if there is an event
-                    // already registed for a thread id, it should be
-                    // the matching start, not a duplicate end.
-                    if (old != null && old.type == ThreadEventType.END) {
-                        throw new IllegalArgumentException("Duplicate ThreadEvent.end for id "
-                                                           + event.threadId);
-                    }
-                    break;
-            }
-            threadHistory.add(event);
-        }
-
-        /**
-         * Record an stack trace and an associated int[] cell of
-         * sample cound for the stack trace. The caller is allowed
-         * retain a pointer to the cell to update the count. The
-         * SamplingProfiler intentionally does not present a mutable
-         * view of the count.
-         */
-        public void addStackTrace(StackTrace stackTrace, int[] countCell) {
-            if (!threadIdToThreadEvent.containsKey(stackTrace.threadId)) {
-                throw new IllegalArgumentException("Unknown thread id " + stackTrace.threadId);
-            }
-            int[] old = stackTraces.put(stackTrace, countCell);
-            if (old != null) {
-                throw new IllegalArgumentException("StackTrace already registered for id "
-                                                   + stackTrace.stackTraceId + ":\n" + stackTrace);
-            }
-        }
-    }
-
-    public static interface HprofWriter {
-        public void write() throws IOException;
-    }
-
-    public static final class AsciiHprofWriter implements HprofWriter {
-
-        private final HprofData data;
-        private final PrintWriter out;
-
-        public AsciiHprofWriter(HprofData data, OutputStream outputStream) {
-            this.data = data;
-            this.out = new PrintWriter(outputStream);
-        }
-
-        public void write() throws IOException {
-            for (HprofData.ThreadEvent e : data.getThreadHistory()) {
-                out.println(e);
-            }
-
-            List<HprofData.Sample> samples
-                    = new ArrayList<HprofData.Sample>(data.getSamples());
-            Collections.sort(samples, SAMPLE_COMPARATOR);
-            int total = 0;
-            for (HprofData.Sample sample : samples) {
-                HprofData.StackTrace stackTrace = sample.stackTrace;
-                int count = sample.count;
-                total += count;
-                out.printf("TRACE %d: (thread=%d)\n",
-                           stackTrace.stackTraceId,
-                           stackTrace.threadId);
-                for (StackTraceElement e : stackTrace.stackFrames) {
-                    out.printf("\t%s\n", e);
-                }
-            }
-            Date now = new Date(data.getStartMillis());
-            // "CPU SAMPLES BEGIN (total = 826) Wed Jul 21 12:03:46 2010"
-            out.printf("CPU SAMPLES BEGIN (total = %d) %ta %tb %td %tT %tY\n",
-                       total, now, now, now, now, now);
-            out.printf("rank   self  accum   count trace method\n");
-            int rank = 0;
-            double accum = 0;
-            for (HprofData.Sample sample : samples) {
-                rank++;
-                HprofData.StackTrace stackTrace = sample.stackTrace;
-                int count = sample.count;
-                double self = (double)count/(double)total;
-                accum += self;
-
-                // "   1 65.62% 65.62%     542 300302 java.lang.Long.parseLong"
-                out.printf("% 4d% 6.2f%%% 6.2f%% % 7d % 5d %s.%s\n",
-                           rank, self*100, accum*100, count, stackTrace.stackTraceId,
-                           stackTrace.stackFrames[0].getClassName(),
-                           stackTrace.stackFrames[0].getMethodName());
-            }
-            out.printf("CPU SAMPLES END\n");
-            out.flush();
-        }
-
-        private static final Comparator<HprofData.Sample> SAMPLE_COMPARATOR
-                = new Comparator<HprofData.Sample>() {
-            public int compare(HprofData.Sample s1, HprofData.Sample s2) {
-                return s2.count - s1.count;
-            }
-        };
-    }
-
-
-    /**
-     * Hprof binary format related constants shared between the
-     * BinaryHprofReader and BinaryHprofWriter.
-     */
-    public static class BinaryHprof {
-        /**
-         * Currently code only supports 4 byte id size.
-         */
-        public static final int ID_SIZE = 4;
-
-        public static enum Tag {
-
-            STRING_IN_UTF8(0x01, -ID_SIZE),
-            LOAD_CLASS(0x02, 4 + ID_SIZE + 4 + ID_SIZE),
-            UNLOAD_CLASS(0x03, 4),
-            STACK_FRAME(0x04, ID_SIZE + ID_SIZE + ID_SIZE + ID_SIZE + 4 + 4),
-            STACK_TRACE(0x05, -(4 + 4 + 4)),
-            ALLOC_SITES(0x06, -(2 + 4 + 4 + 4 + 8 + 8 + 4)),
-            HEAP_SUMMARY(0x07, 4 + 4 + 8 + 8),
-            START_THREAD(0x0a, 4 + ID_SIZE + 4 + ID_SIZE + ID_SIZE + ID_SIZE),
-            END_THREAD(0x0b, 4),
-            HEAP_DUMP(0x0c, -0),
-            HEAP_DUMP_SEGMENT(0x1c, -0),
-            HEAP_DUMP_END(0x2c, 0),
-            CPU_SAMPLES(0x0d, -(4 + 4)),
-            CONTROL_SETTINGS(0x0e, 4 + 2);
-
-            public final byte tag;
-
-            /**
-             * Minimum size in bytes.
-             */
-            public final int minimumSize;
-
-            /**
-             * Maximum size in bytes. 0 mean no specific limit.
-             */
-            public final int maximumSize;
-
-            private Tag(int tag, int size) {
-                this.tag = (byte) tag;
-                if (size > 0) {
-                    // fixed size, max and min the same
-                    this.minimumSize = size;
-                    this.maximumSize = size;
-                } else {
-                    // only minimum bound
-                    this.minimumSize = -size;
-                    this.maximumSize = 0;
-                }
-            }
-
-            private static final Map<Byte, Tag> BYTE_TO_TAG
-                    = new HashMap<Byte, Tag>();
-
-            static {
-                for (Tag v : Tag.values()) {
-                    BYTE_TO_TAG.put(v.tag, v);
-                }
-            }
-
-            public static Tag get(byte tag) {
-                return BYTE_TO_TAG.get(tag);
-            }
-
-            /**
-             * Returns null if the actual size meets expectations, or a
-             * String error message if not.
-             */
-            public String checkSize(int actual) {
-                if (actual < minimumSize) {
-                    return "expected a minimial record size of " + minimumSize + " for " + this
-                            + " but received " + actual;
-                }
-                if (maximumSize == 0) {
-                    return null;
-                }
-                if (actual > maximumSize) {
-                    return "expected a maximum record size of " + maximumSize + " for " + this
-                            + " but received " + actual;
-                }
-                return null;
-            }
-        }
-
-        public static enum ControlSettings {
-            ALLOC_TRACES(0x01),
-            CPU_SAMPLING(0x02);
-
-            public final int bitmask;
-
-            private ControlSettings(int bitmask) {
-                this.bitmask = bitmask;
-            }
-        }
-
-    }
-
-    public static final class BinaryHprofWriter implements HprofWriter {
-
-        private int nextStringId = 1; // id 0 => null
-        private int nextClassId = 1;
-        private int nextStackFrameId = 1;
-        private final Map<String, Integer> stringToId = new HashMap<String, Integer>();
-        private final Map<String, Integer> classNameToId = new HashMap<String, Integer>();
-        private final Map<StackTraceElement, Integer> stackFrameToId
-                = new HashMap<StackTraceElement, Integer>();
-
-        private final HprofData data;
-        private final DataOutputStream out;
-
-        public BinaryHprofWriter(HprofData data, OutputStream outputStream) {
-            this.data = data;
-            this.out = new DataOutputStream(outputStream);
-        }
-
-        public void write() throws IOException {
-            try {
-                writeHeader(data.getStartMillis());
-
-                writeControlSettings(data.getFlags(), data.getDepth());
-
-                for (HprofData.ThreadEvent event : data.getThreadHistory()) {
-                    writeThreadEvent(event);
-                }
-
-                Set<HprofData.Sample> samples = data.getSamples();
-                int total = 0;
-                for (HprofData.Sample sample : samples) {
-                    total += sample.count;
-                    writeStackTrace(sample.stackTrace);
-                }
-                writeCpuSamples(total, samples);
-
-            } finally {
-                out.flush();
-            }
-        }
-
-        private void writeHeader(long dumpTimeInMilliseconds) throws IOException {
-            out.writeBytes("JAVA PROFILE 1.0.2");
-            out.writeByte(0); // null terminated string
-            out.writeInt(BinaryHprof.ID_SIZE);
-            out.writeLong(dumpTimeInMilliseconds);
-        }
-
-        private void writeControlSettings(int flags, int depth) throws IOException {
-            if (depth > Short.MAX_VALUE) {
-                throw new IllegalArgumentException("depth too large for binary hprof: "
-                                                   + depth + " > " + Short.MAX_VALUE);
-            }
-            writeRecordHeader(BinaryHprof.Tag.CONTROL_SETTINGS,
-                              0,
-                              BinaryHprof.Tag.CONTROL_SETTINGS.maximumSize);
-            out.writeInt(flags);
-            out.writeShort((short) depth);
-        }
-
-        private void writeThreadEvent(HprofData.ThreadEvent e) throws IOException {
-            switch (e.type) {
-                case START:
-                    writeStartThread(e);
-                    return;
-                case END:
-                    writeStopThread(e);
-                    return;
-            }
-            throw new IllegalStateException(e.type.toString());
-        }
-
-        private void writeStartThread(HprofData.ThreadEvent e) throws IOException {
-            int threadNameId = writeString(e.threadName);
-            int groupNameId = writeString(e.groupName);
-            int parentGroupNameId = writeString(e.parentGroupName);
-            writeRecordHeader(BinaryHprof.Tag.START_THREAD,
-                              0,
-                              BinaryHprof.Tag.START_THREAD.maximumSize);
-            out.writeInt(e.threadId);
-            writeId(e.objectId);
-            out.writeInt(0); // stack trace where thread was started unavailable
-            writeId(threadNameId);
-            writeId(groupNameId);
-            writeId(parentGroupNameId);
-        }
-
-        private void writeStopThread(HprofData.ThreadEvent e) throws IOException {
-            writeRecordHeader(BinaryHprof.Tag.END_THREAD,
-                              0,
-                              BinaryHprof.Tag.END_THREAD.maximumSize);
-            out.writeInt(e.threadId);
-        }
-
-        private void writeRecordHeader(BinaryHprof.Tag hprofTag,
-                                       int timeDeltaInMicroseconds,
-                                       int recordLength) throws IOException {
-            String error = hprofTag.checkSize(recordLength);
-            if (error != null) {
-                throw new AssertionError(error);
-            }
-            out.writeByte(hprofTag.tag);
-            out.writeInt(timeDeltaInMicroseconds);
-            out.writeInt(recordLength);
-        }
-
-        private void writeId(int id) throws IOException {
-            out.writeInt(id);
-        }
-
-        /**
-         * Ensures that a string has been writen to the out and
-         * returns its ID. The ID of a null string is zero, and
-         * doesn't actually result in any output. In a string has
-         * already been written previously, the earlier ID will be
-         * returned and no output will be written.
-         */
-        private int writeString(String string) throws IOException {
-            if (string == null) {
-                return 0;
-            }
-            Integer identifier = stringToId.get(string);
-            if (identifier != null) {
-                return identifier;
-            }
-
-            int id = nextStringId++;
-            stringToId.put(string, id);
-
-            byte[] bytes = string.getBytes("UTF-8");
-            writeRecordHeader(BinaryHprof.Tag.STRING_IN_UTF8,
-                              0,
-                              BinaryHprof.ID_SIZE + bytes.length);
-            out.writeInt(id);
-            out.write(bytes, 0, bytes.length);
-
-            return id;
-        }
-
-        private void writeCpuSamples(int totalSamples, Set<HprofData.Sample> samples)
-                throws IOException {
-            int samplesCount = samples.size();
-            if (samplesCount == 0) {
-                return;
-            }
-            writeRecordHeader(BinaryHprof.Tag.CPU_SAMPLES, 0, 4 + 4 + (samplesCount * (4 + 4)));
-            out.writeInt(totalSamples);
-            out.writeInt(samplesCount);
-            for (HprofData.Sample sample : samples) {
-                out.writeInt(sample.count);
-                out.writeInt(sample.stackTrace.stackTraceId);
-            }
-        }
-
-        private void writeStackTrace(HprofData.StackTrace stackTrace) throws IOException {
-            int frames = stackTrace.stackFrames.length;
-            int[] stackFrameIds = new int[frames];
-            for (int i = 0; i < frames; i++) {
-                stackFrameIds[i] = writeStackFrame(stackTrace.stackFrames[i]);
-            }
-            writeRecordHeader(BinaryHprof.Tag.STACK_TRACE,
-                              0,
-                              4 + 4 + 4 + (frames * BinaryHprof.ID_SIZE));
-            out.writeInt(stackTrace.stackTraceId);
-            out.writeInt(stackTrace.threadId);
-            out.writeInt(frames);
-            for (int stackFrameId : stackFrameIds) {
-                writeId(stackFrameId);
-            }
-        }
-
-        private int writeLoadClass(String className) throws IOException {
-            Integer identifier = classNameToId.get(className);
-            if (identifier != null) {
-                return identifier;
-            }
-            int id = nextClassId++;
-            classNameToId.put(className, id);
-
-            int classNameId = writeString(className);
-            writeRecordHeader(BinaryHprof.Tag.LOAD_CLASS,
-                              0,
-                              BinaryHprof.Tag.LOAD_CLASS.maximumSize);
-            out.writeInt(id);
-            writeId(0); // class object ID
-            out.writeInt(0); // stack trace where class was loaded is unavailable
-            writeId(classNameId);
-
-            return id;
-        }
-
-        private int writeStackFrame(StackTraceElement stackFrame) throws IOException {
-            Integer identifier = stackFrameToId.get(stackFrame);
-            if (identifier != null) {
-                return identifier;
-            }
-
-            int id = nextStackFrameId++;
-            stackFrameToId.put(stackFrame, id);
-
-            int classId = writeLoadClass(stackFrame.getClassName());
-            int methodNameId = writeString(stackFrame.getMethodName());
-            int sourceId = writeString(stackFrame.getFileName());
-            writeRecordHeader(BinaryHprof.Tag.STACK_FRAME,
-                              0,
-                              BinaryHprof.Tag.STACK_FRAME.maximumSize);
-            writeId(id);
-            writeId(methodNameId);
-            writeId(0); // method signature is unavailable from StackTraceElement
-            writeId(sourceId);
-            out.writeInt(classId);
-            out.writeInt(stackFrame.getLineNumber());
-
-            return id;
-        }
-
-        public void close() throws IOException {
-            out.close();
-        }
-    }
-
-    /**
-     * <pre>   {@code
-     * BinaryHprofReader reader = new BinaryHprofReader(new BufferedInputStream(inputStream));
-     * reader.setStrict(false); // for RI compatability
-     * reader.read();
-     * inputStream.close();
-     * reader.getVersion();
-     * reader.getHprofData();
-     * }</pre>
-     */
-    public static final class BinaryHprofReader {
-
-        private static final boolean TRACE = false;
-
-        private final DataInputStream in;
-
-        /**
-         * By default we try to strictly validate rules followed by
-         * our HprofWriter. For example, every end thread is preceded
-         * by a matching start thread.
-         */
-        private boolean strict = true;
-
-        /**
-         * version string from header after read has been performed,
-         * otherwise null. nullness used to detect if callers try to
-         * access data before read is called.
-         */
-        private String version;
-
-        private final Map<HprofData.StackTrace, int[]> stackTraces
-                = new HashMap<HprofData.StackTrace, int[]>();
-
-        private final HprofData hprofData = new HprofData(stackTraces);
-
-        private final Map<Integer, String> idToString = new HashMap<Integer, String>();
-        private final Map<Integer, String> idToClassName = new HashMap<Integer, String>();
-        private final Map<Integer, StackTraceElement> idToStackFrame
-                = new HashMap<Integer, StackTraceElement>();
-        private final Map<Integer, HprofData.StackTrace> idToStackTrace
-                = new HashMap<Integer, HprofData.StackTrace>();
-
-        /**
-         * Creates a BinaryHprofReader around the specified {@code
-         * inputStream}
-         */
-        public BinaryHprofReader(InputStream inputStream) throws IOException {
-            this.in = new DataInputStream(inputStream);
-        }
-
-        public boolean getStrict () {
-            return strict;
-        }
-
-        public void setStrict (boolean strict) {
-            if (version != null) {
-                throw new IllegalStateException("cannot set strict after read()");
-            }
-            this.strict = strict;
-        }
-
-        /**
-         * throws IllegalStateException if read() has not been called.
-         */
-        private void checkRead() {
-            if (version == null) {
-                throw new IllegalStateException("data access before read()");
-            }
-        }
-
-        public String getVersion() {
-            checkRead();
-            return version;
-        }
-
-        public HprofData getHprofData() {
-            checkRead();
-            return hprofData;
-        }
-
-        /**
-         * Read the hprof header and records from the input
-         */
-        public void read() throws IOException {
-            parseHeader();
-            parseRecords();
-        }
-
-        private void parseHeader() throws IOException {
-            if (TRACE) {
-                System.out.println("hprofTag=HEADER");
-            }
-            parseVersion();
-            parseIdSize();
-            parseTime();
-        }
-
-        private void parseVersion() throws IOException {
-            byte[] bytes = new byte[512];
-            for (int i = 0; i < bytes.length; i++) {
-                byte b = in.readByte();
-                if (b == '\0') {
-                    String version = new String(bytes, 0, i, "UTF-8");
-                    if (TRACE) {
-                        System.out.println("\tversion=" + version);
-                    }
-                    if (!version.startsWith("JAVA PROFILE ")) {
-                        throw new MalformedHprofException("Unexpected version: " + version);
-                    }
-                    this.version = version;
-                    return;
-                }
-                bytes[i] = b;
-            }
-            throw new MalformedHprofException("Could not find HPROF version");
-        }
-
-        private void parseIdSize() throws IOException {
-            int idSize = in.readInt();
-            if (TRACE) {
-                System.out.println("\tidSize=" + idSize);
-            }
-            if (idSize != BinaryHprof.ID_SIZE) {
-                throw new MalformedHprofException("Unsupported identifier size: " + idSize);
-            }
-        }
-
-        private void parseTime() throws IOException {
-            long time = in.readLong();
-            if (TRACE) {
-                System.out.println("\ttime=" + Long.toHexString(time) + " " + new Date(time));
-            }
-            hprofData.setStartMillis(time);
-        }
-
-        private void parseRecords() throws IOException {
-            while (parseRecord()) {
-                ;
-            }
-        }
-
-        /**
-         * Read and process the next record. Returns true if a
-         * record was handled, false on EOF.
-         */
-        private boolean parseRecord() throws IOException {
-            int tagOrEOF = in.read();
-            if (tagOrEOF == -1) {
-                return false;
-            }
-            byte tag = (byte) tagOrEOF;
-            int timeDeltaInMicroseconds = in.readInt();
-            int recordLength = in.readInt();
-            BinaryHprof.Tag hprofTag = BinaryHprof.Tag.get(tag);
-            if (TRACE) {
-                System.out.println("hprofTag=" + hprofTag);
-            }
-            if (hprofTag == null) {
-                skipRecord(hprofTag, recordLength);
-                return true;
-            }
-            String error = hprofTag.checkSize(recordLength);
-            if (error != null) {
-                throw new MalformedHprofException(error);
-            }
-            switch (hprofTag) {
-                case CONTROL_SETTINGS:
-                    parseControlSettings();
-                    return true;
-
-                case STRING_IN_UTF8:
-                    parseStringInUtf8(recordLength);
-                    return true;
-
-                case START_THREAD:
-                    parseStartThread();
-                    return true;
-                case END_THREAD:
-                    parseEndThread();
-                    return true;
-
-                case LOAD_CLASS:
-                    parseLoadClass();
-                    return true;
-                case STACK_FRAME:
-                    parseStackFrame();
-                    return true;
-                case STACK_TRACE:
-                    parseStackTrace(recordLength);
-                    return true;
-
-                case CPU_SAMPLES:
-                    parseCpuSamples(recordLength);
-                    return true;
-
-                case UNLOAD_CLASS:
-                case ALLOC_SITES:
-                case HEAP_SUMMARY:
-                case HEAP_DUMP:
-                case HEAP_DUMP_SEGMENT:
-                case HEAP_DUMP_END:
-                default:
-                    skipRecord(hprofTag, recordLength);
-                    return true;
-            }
-        }
-
-        private void skipRecord(BinaryHprof.Tag hprofTag, long recordLength) throws IOException {
-            if (TRACE) {
-                System.out.println("\tskipping recordLength=" + recordLength);
-            }
-            long skipped = in.skip(recordLength);
-            if (skipped != recordLength) {
-                throw new EOFException("Expected to skip " + recordLength
-                                       + " bytes but only skipped " + skipped + " bytes");
-            }
-        }
-
-        private void parseControlSettings() throws IOException {
-            int flags = in.readInt();
-            short depth = in.readShort();
-            if (TRACE) {
-                System.out.println("\tflags=" + Integer.toHexString(flags));
-                System.out.println("\tdepth=" + depth);
-            }
-            hprofData.setFlags(flags);
-            hprofData.setDepth(depth);
-        }
-
-        private void parseStringInUtf8(int recordLength) throws IOException {
-            int stringId = in.readInt();
-            byte[] bytes = new byte[recordLength - BinaryHprof.ID_SIZE];
-            in.read(bytes);
-            String string = new String(bytes, "UTF-8");
-            if (TRACE) {
-                System.out.println("\tstring=" + string);
-            }
-            String old = idToString.put(stringId, string);
-            if (old != null) {
-                throw new MalformedHprofException("Duplicate string id: " + stringId);
-            }
-        }
-
-        private void parseLoadClass() throws IOException {
-            int classId = in.readInt();
-            int classObjectId = readId();
-            // serial number apparently not a stack trace id. (int vs ID)
-            // we don't use this field.
-            int stackTraceSerialNumber = in.readInt();
-            String className = readString();
-            if (TRACE) {
-                System.out.println("\tclassId=" + classId);
-                System.out.println("\tclassObjectId=" + classObjectId);
-                System.out.println("\tstackTraceSerialNumber=" + stackTraceSerialNumber);
-                System.out.println("\tclassName=" + className);
-            }
-            String old = idToClassName.put(classId, className);
-            if (old != null) {
-                throw new MalformedHprofException("Duplicate class id: " + classId);
-            }
-        }
-
-        private int readId() throws IOException {
-            return in.readInt();
-        }
-
-        private String readString() throws IOException {
-            int id = readId();
-            if (id == 0) {
-                return null;
-            }
-            String string = idToString.get(id);
-            if (string == null) {
-                throw new MalformedHprofException("Unknown string id " + id);
-            }
-            return string;
-        }
-
-        private String readClass() throws IOException {
-            int id = readId();
-            String string = idToClassName.get(id);
-            if (string == null) {
-                throw new MalformedHprofException("Unknown class id " + id);
-            }
-            return string;
-        }
-
-        private void parseStartThread() throws IOException {
-            int threadId = in.readInt();
-            int objectId = readId();
-            // stack trace where thread was created.
-            // serial number apparently not a stack trace id. (int vs ID)
-            // we don't use this field.
-            int stackTraceSerialNumber = in.readInt();
-            String threadName = readString();
-            String groupName = readString();
-            String parentGroupName = readString();
-            if (TRACE) {
-                System.out.println("\tthreadId=" + threadId);
-                System.out.println("\tobjectId=" + objectId);
-                System.out.println("\tstackTraceSerialNumber=" + stackTraceSerialNumber);
-                System.out.println("\tthreadName=" + threadName);
-                System.out.println("\tgroupName=" + groupName);
-                System.out.println("\tparentGroupName=" + parentGroupName);
-            }
-            HprofData.ThreadEvent event
-                    = HprofData.ThreadEvent.start(objectId, threadId,
-                                                  threadName, groupName, parentGroupName);
-            hprofData.addThreadEvent(event);
-        }
-
-        private void parseEndThread() throws IOException {
-            int threadId = in.readInt();
-            if (TRACE) {
-                System.out.println("\tthreadId=" + threadId);
-            }
-            HprofData.ThreadEvent event = HprofData.ThreadEvent.end(threadId);
-            hprofData.addThreadEvent(event);
-        }
-
-        private void parseStackFrame() throws IOException {
-            int stackFrameId = readId();
-            String methodName = readString();
-            String methodSignature = readString();
-            String file = readString();
-            String className = readClass();
-            int line = in.readInt();
-            if (TRACE) {
-                System.out.println("\tstackFrameId=" + stackFrameId);
-                System.out.println("\tclassName=" + className);
-                System.out.println("\tmethodName=" + methodName);
-                System.out.println("\tmethodSignature=" + methodSignature);
-                System.out.println("\tfile=" + file);
-                System.out.println("\tline=" + line);
-            }
-            StackTraceElement stackFrame = new StackTraceElement(className, methodName, file, line);
-            StackTraceElement old = idToStackFrame.put(stackFrameId, stackFrame);
-            if (old != null) {
-                throw new MalformedHprofException("Duplicate stack frame id: " + stackFrameId);
-            }
-        }
-
-        private void parseStackTrace(int recordLength) throws IOException {
-            int stackTraceId = in.readInt();
-            int threadId = in.readInt();
-            int frames = in.readInt();
-            if (TRACE) {
-                System.out.println("\tstackTraceId=" + stackTraceId);
-                System.out.println("\tthreadId=" + threadId);
-                System.out.println("\tframes=" + frames);
-            }
-            int expectedLength = 4 + 4 + 4 + (frames * BinaryHprof.ID_SIZE);
-            if (recordLength != expectedLength) {
-                throw new MalformedHprofException("Expected stack trace record of size "
-                                                  + expectedLength
-                                                  + " based on number of frames but header "
-                                                  + "specified a length of  " + recordLength);
-            }
-            StackTraceElement[] stackFrames = new StackTraceElement[frames];
-            for (int i = 0; i < frames; i++) {
-                int stackFrameId = readId();
-                StackTraceElement stackFrame = idToStackFrame.get(stackFrameId);
-                if (TRACE) {
-                    System.out.println("\tstackFrameId=" + stackFrameId);
-                    System.out.println("\tstackFrame=" + stackFrame);
-                }
-                if (stackFrame == null) {
-                    throw new MalformedHprofException("Unknown stack frame id " + stackFrameId);
-                }
-                stackFrames[i] = stackFrame;
-            }
-
-            HprofData.StackTrace stackTrace
-                    = new HprofData.StackTrace(stackTraceId, threadId, stackFrames);
-            if (strict) {
-                hprofData.addStackTrace(stackTrace, new int[1]);
-            } else {
-                // The RI can have duplicate stacks, presumably they
-                // have a minor race if two samples with the same
-                // stack are taken around the same time. if we have a
-                // duplicate, just skip adding it to hprofData, but
-                // register it locally in idToStackFrame. if it seen
-                // in CPU_SAMPLES, we will find a StackTrace is equal
-                // to the first, so they will share a countCell.
-                int[] countCell = stackTraces.get(stackTrace);
-                if (countCell == null) {
-                    hprofData.addStackTrace(stackTrace, new int[1]);
-                }
-            }
-
-            HprofData.StackTrace old = idToStackTrace.put(stackTraceId, stackTrace);
-            if (old != null) {
-                throw new MalformedHprofException("Duplicate stack trace id: " + stackTraceId);
-            }
-
-        }
-
-        private void parseCpuSamples(int recordLength) throws IOException {
-            int totalSamples = in.readInt();
-            int samplesCount = in.readInt();
-            if (TRACE) {
-                System.out.println("\ttotalSamples=" + totalSamples);
-                System.out.println("\tsamplesCount=" + samplesCount);
-            }
-            int expectedLength = 4 + 4 + (samplesCount * (4 + 4));
-            if (recordLength != expectedLength) {
-                throw new MalformedHprofException("Expected CPU samples record of size "
-                                                  + expectedLength
-                                                  + " based on number of samples but header "
-                                                  + "specified a length of  " + recordLength);
-            }
-            int total = 0;
-            for (int i = 0; i < samplesCount; i++) {
-                int count = in.readInt();
-                int stackTraceId = in.readInt();
-                if (TRACE) {
-                    System.out.println("\tcount=" + count);
-                    System.out.println("\tstackTraceId=" + stackTraceId);
-                }
-                HprofData.StackTrace stackTrace = idToStackTrace.get(stackTraceId);
-                if (stackTrace == null) {
-                    throw new MalformedHprofException("Unknown stack trace id " + stackTraceId);
-                }
-                if (count == 0) {
-                    throw new MalformedHprofException("Zero sample count for stack trace "
-                                                      + stackTrace);
-                }
-                int[] countCell = stackTraces.get(stackTrace);
-                if (strict) {
-                    if (countCell[0] != 0) {
-                        throw new MalformedHprofException("Setting sample count of stack trace "
-                                                          + stackTrace + " to " + count
-                                                          + " found it was already initialized to "
-                                                          + countCell[0]);
-                    }
-                } else {
-                    // Coalesce counts from duplicate stack traces.
-                    // For more on this, see comments in parseStackTrace.
-                    count += countCell[0];
-                }
-                countCell[0] = count;
-                total += count;
-            }
-            if (strict && totalSamples != total) {
-                throw new MalformedHprofException("Expected a total of " + totalSamples
-                                                  + " samples but saw " + total);
-            }
-        }
-    }
-
-    public static final class MalformedHprofException extends IOException {
-        private MalformedHprofException(String message) {
-            super(message);
-        }
-        private MalformedHprofException(String message, Throwable cause) {
-            super(message, cause);
-        }
-        private MalformedHprofException(Throwable cause) {
-            super(cause);
-        }
-    }
-
-    /**
-     * Run on device with:
-     * adb shell dalvikvm 'dalvik.system.SamplingProfiler\$HprofBinaryToAscii'
-     *
-     * Run on host with:
-     * java -classpath out/target/common/obj/JAVA_LIBRARIES/core_intermediates/classes.jar
-     */
-    public static final class HprofBinaryToAscii {
-
-        public static void main(String[] args) {
-            System.exit(convert(args) ? 0 : 1);
-        }
-
-        public static boolean convert(String[] args) {
-
-            if (args.length != 1) {
-                usage("binary hprof file argument expected");
-                return false;
-            }
-            File file = new File(args[0]);
-            if (!file.exists()) {
-                usage("file " + file + " does not exist");
-                return false;
-            }
-
-            HprofData hprofData;
-            InputStream inputStream = null;
-            try {
-                inputStream = new BufferedInputStream(new FileInputStream(file));
-                BinaryHprofReader reader = new BinaryHprofReader(inputStream);
-                reader.setStrict(false);
-                reader.read();
-                hprofData = reader.getHprofData();
-            } catch (IOException e) {
-                System.out.println("Problem reading binary hprof data from "
-                                   + file + ": " + e.getMessage());
-                return false;
-            } finally {
-                IoUtils.closeQuietly(inputStream);
-            }
-            try {
-                HprofWriter writer = new AsciiHprofWriter(hprofData, System.out);
-                writer.write();
-            } catch (IOException e) {
-                System.out.println("Problem writing ASCII hprof data: " + e.getMessage());
-                return false;
-            }
-            return true;
-        }
-
-        private static void usage(String error) {
-            System.out.print("ERROR: ");
-            System.out.println(error);
-            System.out.println();
-            System.out.println("usage: HprofBinaryToAscii <binary-hprof-file>");
-            System.out.println();
-            System.out.println("Reads a binary hprof file and print it in ASCII format");
-        }
-    }
-
-    /**
-     * Map of stack traces to a mutable sample count.
-     */
-    private final Map<HprofData.StackTrace, int[]> stackTraces
-            = new HashMap<HprofData.StackTrace, int[]>();
-
-    /**
-     * Data collected by the sampling profiler
-     */
-    private final HprofData hprofData = new HprofData(stackTraces);
-
-    /**
-     * Timer that is used for the lifetime of the profiler
-     */
-    // note that dalvik/vm/Thread.c depends on this name
-    private final Timer timer = new Timer("SamplingProfiler", true);
-
-    /**
-     * A sampler is created every time profiling starts and cleared
-     * everytime profiling stops because once a {@code TimerTask} is
-     * canceled it cannot be reused.
-     */
-    private TimerTask sampler;
-
-    /**
-     * The maximum number of {@code StackTraceElements} to retain in
-     * each stack.
-     */
-    private final int depth;
-
-    /**
-     * The {@code ThreadSet} that identifies which threads to sample.
-     */
-    private final ThreadSet threadSet;
-
-    /*
-     *  Real hprof output examples don't start the thread and trace
-     *  identifiers at one but seem to start at these arbitrary
-     *  constants. It certainly seems useful to have relatively unique
-     *  identifers when manual searching hprof output.
-     */
-    private int nextThreadId = 200001;
-    private int nextStackTraceId = 300001;
-    private int nextObjectId = 1;
-
-    /**
-     * The threads currently known to the profiler for detecting
-     * thread start and end events.
-     */
-    private Thread[] currentThreads = new Thread[0];
-
-    /**
-     * Map of currently active threads to their identifiers. When
-     * threads disappear they are removed and only referenced by their
-     * identifiers to prevent retaining garbage threads.
-     */
-    private final Map<Thread, Integer> threadIds = new HashMap<Thread, Integer>();
-
-    /**
-     * Mutable StackTrace that is used for probing stackTraces Map
-     * without allocating a StackTrace. If addStackTrace needs to
-     * be thread safe, this would need to be reconsidered.
-     */
-    private final HprofData.StackTrace mutableStackTrace = new HprofData.StackTrace();
-
-    /**
-     * Create a sampling profiler that collects stacks with the
-     * specified depth from the threads specified by the specified
-     * thread collector.
-     *
-     * @param depth The maximum stack depth to retain for each sample
-     * similar to the hprof option of the same name. Any stack deeper
-     * than this will be truncated to this depth. A good starting
-     * value is 4 although it is not uncommon to need to raise this to
-     * get enough context to understand program behavior. While
-     * programs with extensive recursion may require a high value for
-     * depth, simply passing in a value for Integer.MAX_VALUE is not
-     * advised because of the significant memory need to retain such
-     * stacks and runtime overhead to compare stacks.
-     */
-    public SamplingProfiler(int depth, ThreadSet threadSet) {
-        this.depth = depth;
-        this.threadSet = threadSet;
-        hprofData.setFlags(BinaryHprof.ControlSettings.CPU_SAMPLING.bitmask);
-        hprofData.setDepth(depth);
-    }
-
-    /**
-     * A ThreadSet specifies the set of threads to sample.
-     */
-    public static interface ThreadSet {
-        /**
-         * Returns an array containing the threads to be sampled. The
-         * array may be longer than the number of threads to be
-         * sampled, in which case the extra elements must be null.
-         */
-        public Thread[] threads();
-    }
-
-    /**
-     * Returns a ThreadSet for a fixed set of threads that will not
-     * vary at runtime. This has less overhead than a dynamically
-     * calculated set, such as {@link newThreadGroupTheadSet}, which has
-     * to enumerate the threads each time profiler wants to collect
-     * samples.
-     */
-    public static ThreadSet newArrayThreadSet(Thread... threads) {
-        return new ArrayThreadSet(threads);
-    }
-
-    /**
-     * An ArrayThreadSet samples a fixed set of threads that does not
-     * vary over the life of the profiler.
-     */
-    private static class ArrayThreadSet implements ThreadSet {
-        private final Thread[] threads;
-        public ArrayThreadSet(Thread... threads) {
-            if (threads == null) {
-                throw new NullPointerException("threads == null");
-            }
-            this.threads = threads;
-        }
-        public Thread[] threads() {
-            return threads;
-        }
-    }
-
-    /**
-     * Returns a ThreadSet that is dynamically computed based on the
-     * threads found in the specified ThreadGroup and that
-     * ThreadGroup's children.
-     */
-    public static ThreadSet newThreadGroupTheadSet(ThreadGroup threadGroup) {
-        return new ThreadGroupThreadSet(threadGroup);
-    }
-
-    /**
-     * An ThreadGroupThreadSet sample the threads from the specified
-     * ThreadGroup and the ThreadGroup's children
-     */
-    private static class ThreadGroupThreadSet implements ThreadSet {
-        private final ThreadGroup threadGroup;
-        private Thread[] threads;
-        private int lastThread;
-
-        public ThreadGroupThreadSet(ThreadGroup threadGroup) {
-            if (threadGroup == null) {
-                throw new NullPointerException("threadGroup == null");
-            }
-            this.threadGroup = threadGroup;
-            resize();
-        }
-
-        private void resize() {
-            int count = threadGroup.activeCount();
-            // we can only tell if we had enough room for all active
-            // threads if we actually are larger than the the number of
-            // active threads. making it larger also leaves us room to
-            // tolerate additional threads without resizing.
-            threads = new Thread[count*2];
-            lastThread = 0;
-        }
-
-        public Thread[] threads() {
-            int threadCount;
-            while (true) {
-                threadCount = threadGroup.enumerate(threads);
-                if (threadCount == threads.length) {
-                    resize();
-                } else {
-                    break;
-                }
-            }
-            if (threadCount < lastThread) {
-                // avoid retaining pointers to threads that have ended
-                Arrays.fill(threads, threadCount, lastThread, null);
-            }
-            lastThread = threadCount;
-            return threads;
-        }
-    }
-
-    /**
-     * Starts profiler sampling at the specified rate.
-     *
-     * @param interval The number of milliseconds between samples
-     */
-    public void start(int interval) {
-        if (interval < 1) {
-            throw new IllegalArgumentException("interval < 1");
-        }
-        if (sampler != null) {
-            throw new IllegalStateException("profiling already started");
-        }
-        sampler = new Sampler();
-        hprofData.setStartMillis(System.currentTimeMillis());
-        timer.scheduleAtFixedRate(sampler, 0, interval);
-    }
-
-    /**
-     * Stops profiler sampling. It can be restarted with {@link
-     * #start(int)} to continue sampling.
-     */
-    public void stop() {
-        if (sampler == null) {
-            return;
-        }
-        sampler.cancel();
-        sampler = null;
-    }
-
-    /**
-     * Shuts down profiling after which it can not be restarted. It is
-     * important to shut down profiling when done to free resources
-     * used by the profiler. Shutting down the profiler also stops the
-     * profiling if that has not already been done.
-     */
-    public void shutdown() {
-        stop();
-        timer.cancel();
-    }
-
-    /**
-     * Returns the hprof data accumulated by the profiler since it was
-     * created. The profiler needs to be stopped, but not necessarily
-     * shut down, in order to access the data. If the profiler is
-     * restarted, there is no thread safe way to access the data.
-     */
-    public HprofData getHprofData() {
-        if (sampler != null) {
-            throw new IllegalStateException("cannot access hprof data while sampling");
-        }
-        return hprofData;
-    }
-
-    /**
-     * The Sampler does the real work of the profiler.
-     *
-     * At every sample time, it asks the thread set for the set
-     * of threads to sample. It maintains a history of thread creation
-     * and death events based on changes observed to the threads
-     * returned by the {@code ThreadSet}.
-     *
-     * For each thread to be sampled, a stack is collected and used to
-     * update the set of collected samples. Stacks are truncated to a
-     * maximum depth. There is no way to tell if a stack has been truncated.
-     */
-    private class Sampler extends TimerTask {
-
-        private Thread timerThread;
-
-        public void run() {
-            if (timerThread == null) {
-                timerThread = Thread.currentThread();
-            }
-
-            // process thread creation and death first so that we
-            // assign thread ids to any new threads before allocating
-            // new stacks for them
-            Thread[] newThreads = threadSet.threads();
-            if (!Arrays.equals(currentThreads, newThreads)) {
-                updateThreadHistory(currentThreads, newThreads);
-                currentThreads = newThreads.clone();
-            }
-
-            for (Thread thread : currentThreads) {
-                if (thread == null) {
-                    break;
-                }
-                if (thread == timerThread) {
-                    continue;
-                }
-
-                // TODO replace with a VMStack.getThreadStackTrace
-                // variant to avoid allocating unneeded elements
-                StackTraceElement[] stackFrames = thread.getStackTrace();
-                if (stackFrames.length == 0) {
-                    continue;
-                }
-                if (stackFrames.length > depth) {
-                    stackFrames = Arrays.copyOfRange(stackFrames, 0, depth);
-                }
-                recordStackTrace(thread, stackFrames);
-            }
-        }
-
-        /**
-         * Record a new stack trace. The thread should have been
-         * previously registered with addStartThread.
-         */
-        private void recordStackTrace(Thread thread, StackTraceElement[] stackFrames) {
-            Integer threadId = threadIds.get(thread);
-            if (threadId == null) {
-                throw new IllegalArgumentException("Unknown thread " + thread);
-            }
-            mutableStackTrace.threadId = threadId;
-            mutableStackTrace.stackFrames = stackFrames;
-
-            int[] countCell = stackTraces.get(mutableStackTrace);
-            if (countCell == null) {
-                countCell = new int[1];
-                HprofData.StackTrace stackTrace
-                        = new HprofData.StackTrace(nextStackTraceId++, threadId, stackFrames);
-                hprofData.addStackTrace(stackTrace, countCell);
-            }
-            countCell[0]++;
-        }
-
-        private void updateThreadHistory(Thread[] oldThreads, Thread[] newThreads) {
-            // thread start/stop shouldn't happen too often and
-            // these aren't too big, so hopefully this approach
-            // won't be too slow...
-            Set<Thread> n = new HashSet<Thread>(Arrays.asList(newThreads));
-            Set<Thread> o = new HashSet<Thread>(Arrays.asList(oldThreads));
-
-            // added = new-old
-            Set<Thread> added = new HashSet<Thread>(n);
-            added.removeAll(o);
-
-            // removed = old-new
-            Set<Thread> removed = new HashSet<Thread>(o);
-            removed.removeAll(n);
-
-            for (Thread thread : added) {
-                if (thread == null) {
-                    continue;
-                }
-                if (thread == timerThread) {
-                    continue;
-                }
-                addStartThread(thread);
-            }
-            for (Thread thread : removed) {
-                if (thread == null) {
-                    continue;
-                }
-                if (thread == timerThread) {
-                    continue;
-                }
-                addEndThread(thread);
-            }
-        }
-
-        /**
-         * Record that a newly noticed thread.
-         */
-        private void addStartThread(Thread thread) {
-            if (thread == null) {
-                throw new NullPointerException("thread == null");
-            }
-            int threadId = nextThreadId++;
-            Integer old = threadIds.put(thread, threadId);
-            if (old != null) {
-                throw new IllegalArgumentException("Thread already registered as " + old);
-            }
-
-            String threadName = thread.getName();
-            // group will become null when thread is terminated
-            ThreadGroup group = thread.getThreadGroup();
-            String groupName = group == null ? null : group.getName();
-            ThreadGroup parentGroup = group == null ? null : group.getParent();
-            String parentGroupName = parentGroup == null ? null : parentGroup.getName();
-
-            HprofData.ThreadEvent event
-                    = HprofData.ThreadEvent.start(nextObjectId++, threadId,
-                                                  threadName, groupName, parentGroupName);
-            hprofData.addThreadEvent(event);
-        }
-
-        /**
-         * Record that a thread has disappeared.
-         */
-        private void addEndThread(Thread thread) {
-            if (thread == null) {
-                throw new NullPointerException("thread == null");
-            }
-            Integer threadId = threadIds.remove(thread);
-            if (threadId == null) {
-                throw new IllegalArgumentException("Unknown thread " + thread);
-            }
-            HprofData.ThreadEvent event = HprofData.ThreadEvent.end(threadId);
-            hprofData.addThreadEvent(event);
-        }
-    }
-}
diff --git a/dalvik/src/main/java/dalvik/system/profiler/AsciiHprofWriter.java b/dalvik/src/main/java/dalvik/system/profiler/AsciiHprofWriter.java
new file mode 100644
index 0000000..130d032
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/AsciiHprofWriter.java
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Date;
+import java.util.List;
+
+public final class AsciiHprofWriter implements HprofWriter {
+
+    private final HprofData data;
+    private final PrintWriter out;
+
+    public AsciiHprofWriter(HprofData data, OutputStream outputStream) {
+        this.data = data;
+        this.out = new PrintWriter(outputStream);
+    }
+
+    public void write() throws IOException {
+        for (HprofData.ThreadEvent e : data.getThreadHistory()) {
+            out.println(e);
+        }
+
+        List<HprofData.Sample> samples
+                = new ArrayList<HprofData.Sample>(data.getSamples());
+        Collections.sort(samples, SAMPLE_COMPARATOR);
+        int total = 0;
+        for (HprofData.Sample sample : samples) {
+            HprofData.StackTrace stackTrace = sample.stackTrace;
+            int count = sample.count;
+            total += count;
+            out.printf("TRACE %d: (thread=%d)\n",
+                       stackTrace.stackTraceId,
+                       stackTrace.threadId);
+            for (StackTraceElement e : stackTrace.stackFrames) {
+                out.printf("\t%s\n", e);
+            }
+        }
+        Date now = new Date(data.getStartMillis());
+        // "CPU SAMPLES BEGIN (total = 826) Wed Jul 21 12:03:46 2010"
+        out.printf("CPU SAMPLES BEGIN (total = %d) %ta %tb %td %tT %tY\n",
+                   total, now, now, now, now, now);
+        out.printf("rank   self  accum   count trace method\n");
+        int rank = 0;
+        double accum = 0;
+        for (HprofData.Sample sample : samples) {
+            rank++;
+            HprofData.StackTrace stackTrace = sample.stackTrace;
+            int count = sample.count;
+            double self = (double)count/(double)total;
+            accum += self;
+
+            // "   1 65.62% 65.62%     542 300302 java.lang.Long.parseLong"
+            out.printf("% 4d% 6.2f%%% 6.2f%% % 7d % 5d %s.%s\n",
+                       rank, self*100, accum*100, count, stackTrace.stackTraceId,
+                       stackTrace.stackFrames[0].getClassName(),
+                       stackTrace.stackFrames[0].getMethodName());
+        }
+        out.printf("CPU SAMPLES END\n");
+        out.flush();
+    }
+
+    private static final Comparator<HprofData.Sample> SAMPLE_COMPARATOR
+            = new Comparator<HprofData.Sample>() {
+        public int compare(HprofData.Sample s1, HprofData.Sample s2) {
+            return s2.count - s1.count;
+        }
+    };
+}
diff --git a/dalvik/src/main/java/dalvik/system/profiler/BinaryHprof.java b/dalvik/src/main/java/dalvik/system/profiler/BinaryHprof.java
new file mode 100644
index 0000000..26eb290
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/BinaryHprof.java
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Hprof binary format related constants shared between the
+ * BinaryHprofReader and BinaryHprofWriter.
+ */
+public final class BinaryHprof {
+    /**
+     * Currently code only supports 4 byte id size.
+     */
+    public static final int ID_SIZE = 4;
+
+    public static enum Tag {
+
+        STRING_IN_UTF8(0x01, -ID_SIZE),
+        LOAD_CLASS(0x02, 4 + ID_SIZE + 4 + ID_SIZE),
+        UNLOAD_CLASS(0x03, 4),
+        STACK_FRAME(0x04, ID_SIZE + ID_SIZE + ID_SIZE + ID_SIZE + 4 + 4),
+        STACK_TRACE(0x05, -(4 + 4 + 4)),
+        ALLOC_SITES(0x06, -(2 + 4 + 4 + 4 + 8 + 8 + 4)),
+        HEAP_SUMMARY(0x07, 4 + 4 + 8 + 8),
+        START_THREAD(0x0a, 4 + ID_SIZE + 4 + ID_SIZE + ID_SIZE + ID_SIZE),
+        END_THREAD(0x0b, 4),
+        HEAP_DUMP(0x0c, -0),
+        HEAP_DUMP_SEGMENT(0x1c, -0),
+        HEAP_DUMP_END(0x2c, 0),
+        CPU_SAMPLES(0x0d, -(4 + 4)),
+        CONTROL_SETTINGS(0x0e, 4 + 2);
+
+        public final byte tag;
+
+        /**
+         * Minimum size in bytes.
+         */
+        public final int minimumSize;
+
+        /**
+         * Maximum size in bytes. 0 mean no specific limit.
+         */
+        public final int maximumSize;
+
+        private Tag(int tag, int size) {
+            this.tag = (byte) tag;
+            if (size > 0) {
+                // fixed size, max and min the same
+                this.minimumSize = size;
+                this.maximumSize = size;
+            } else {
+                // only minimum bound
+                this.minimumSize = -size;
+                this.maximumSize = 0;
+            }
+        }
+
+        private static final Map<Byte, Tag> BYTE_TO_TAG
+                = new HashMap<Byte, Tag>();
+
+        static {
+            for (Tag v : Tag.values()) {
+                BYTE_TO_TAG.put(v.tag, v);
+            }
+        }
+
+        public static Tag get(byte tag) {
+            return BYTE_TO_TAG.get(tag);
+        }
+
+        /**
+         * Returns null if the actual size meets expectations, or a
+         * String error message if not.
+         */
+        public String checkSize(int actual) {
+            if (actual < minimumSize) {
+                return "expected a minimial record size of " + minimumSize + " for " + this
+                        + " but received " + actual;
+            }
+            if (maximumSize == 0) {
+                return null;
+            }
+            if (actual > maximumSize) {
+                return "expected a maximum record size of " + maximumSize + " for " + this
+                        + " but received " + actual;
+            }
+            return null;
+        }
+    }
+
+    public static enum ControlSettings {
+        ALLOC_TRACES(0x01),
+        CPU_SAMPLING(0x02);
+
+        public final int bitmask;
+
+        private ControlSettings(int bitmask) {
+            this.bitmask = bitmask;
+        }
+    }
+
+}
diff --git a/dalvik/src/main/java/dalvik/system/profiler/BinaryHprofReader.java b/dalvik/src/main/java/dalvik/system/profiler/BinaryHprofReader.java
new file mode 100644
index 0000000..65e5178
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/BinaryHprofReader.java
@@ -0,0 +1,489 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.io.BufferedInputStream;
+import java.io.DataInputStream;
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * <pre>   {@code
+ * BinaryHprofReader reader = new BinaryHprofReader(new BufferedInputStream(inputStream));
+ * reader.setStrict(false); // for RI compatability
+ * reader.read();
+ * inputStream.close();
+ * reader.getVersion();
+ * reader.getHprofData();
+ * }</pre>
+ */
+public final class BinaryHprofReader {
+
+    private static final boolean TRACE = false;
+
+    private final DataInputStream in;
+
+    /**
+     * By default we try to strictly validate rules followed by
+     * our HprofWriter. For example, every end thread is preceded
+     * by a matching start thread.
+     */
+    private boolean strict = true;
+
+    /**
+     * version string from header after read has been performed,
+     * otherwise null. nullness used to detect if callers try to
+     * access data before read is called.
+     */
+    private String version;
+
+    private final Map<HprofData.StackTrace, int[]> stackTraces
+            = new HashMap<HprofData.StackTrace, int[]>();
+
+    private final HprofData hprofData = new HprofData(stackTraces);
+
+    private final Map<Integer, String> idToString = new HashMap<Integer, String>();
+    private final Map<Integer, String> idToClassName = new HashMap<Integer, String>();
+    private final Map<Integer, StackTraceElement> idToStackFrame
+            = new HashMap<Integer, StackTraceElement>();
+    private final Map<Integer, HprofData.StackTrace> idToStackTrace
+            = new HashMap<Integer, HprofData.StackTrace>();
+
+    /**
+     * Creates a BinaryHprofReader around the specified {@code
+     * inputStream}
+     */
+    public BinaryHprofReader(InputStream inputStream) throws IOException {
+        this.in = new DataInputStream(inputStream);
+    }
+
+    public boolean getStrict () {
+        return strict;
+    }
+
+    public void setStrict (boolean strict) {
+        if (version != null) {
+            throw new IllegalStateException("cannot set strict after read()");
+        }
+        this.strict = strict;
+    }
+
+    /**
+     * throws IllegalStateException if read() has not been called.
+     */
+    private void checkRead() {
+        if (version == null) {
+            throw new IllegalStateException("data access before read()");
+        }
+    }
+
+    public String getVersion() {
+        checkRead();
+        return version;
+    }
+
+    public HprofData getHprofData() {
+        checkRead();
+        return hprofData;
+    }
+
+    /**
+     * Read the hprof header and records from the input
+     */
+    public void read() throws IOException {
+        parseHeader();
+        parseRecords();
+    }
+
+    private void parseHeader() throws IOException {
+        if (TRACE) {
+            System.out.println("hprofTag=HEADER");
+        }
+        parseVersion();
+        parseIdSize();
+        parseTime();
+    }
+
+    private void parseVersion() throws IOException {
+        byte[] bytes = new byte[512];
+        for (int i = 0; i < bytes.length; i++) {
+            byte b = in.readByte();
+            if (b == '\0') {
+                String version = new String(bytes, 0, i, "UTF-8");
+                if (TRACE) {
+                    System.out.println("\tversion=" + version);
+                }
+                if (!version.startsWith("JAVA PROFILE ")) {
+                    throw new MalformedHprofException("Unexpected version: " + version);
+                }
+                this.version = version;
+                return;
+            }
+            bytes[i] = b;
+        }
+        throw new MalformedHprofException("Could not find HPROF version");
+    }
+
+    private void parseIdSize() throws IOException {
+        int idSize = in.readInt();
+        if (TRACE) {
+            System.out.println("\tidSize=" + idSize);
+        }
+        if (idSize != BinaryHprof.ID_SIZE) {
+            throw new MalformedHprofException("Unsupported identifier size: " + idSize);
+        }
+    }
+
+    private void parseTime() throws IOException {
+        long time = in.readLong();
+        if (TRACE) {
+            System.out.println("\ttime=" + Long.toHexString(time) + " " + new Date(time));
+        }
+        hprofData.setStartMillis(time);
+    }
+
+    private void parseRecords() throws IOException {
+        while (parseRecord()) {
+            ;
+        }
+    }
+
+    /**
+     * Read and process the next record. Returns true if a
+     * record was handled, false on EOF.
+     */
+    private boolean parseRecord() throws IOException {
+        int tagOrEOF = in.read();
+        if (tagOrEOF == -1) {
+            return false;
+        }
+        byte tag = (byte) tagOrEOF;
+        int timeDeltaInMicroseconds = in.readInt();
+        int recordLength = in.readInt();
+        BinaryHprof.Tag hprofTag = BinaryHprof.Tag.get(tag);
+        if (TRACE) {
+            System.out.println("hprofTag=" + hprofTag);
+        }
+        if (hprofTag == null) {
+            skipRecord(hprofTag, recordLength);
+            return true;
+        }
+        String error = hprofTag.checkSize(recordLength);
+        if (error != null) {
+            throw new MalformedHprofException(error);
+        }
+        switch (hprofTag) {
+            case CONTROL_SETTINGS:
+                parseControlSettings();
+                return true;
+
+            case STRING_IN_UTF8:
+                parseStringInUtf8(recordLength);
+                return true;
+
+            case START_THREAD:
+                parseStartThread();
+                return true;
+            case END_THREAD:
+                parseEndThread();
+                return true;
+
+            case LOAD_CLASS:
+                parseLoadClass();
+                return true;
+            case STACK_FRAME:
+                parseStackFrame();
+                return true;
+            case STACK_TRACE:
+                parseStackTrace(recordLength);
+                return true;
+
+            case CPU_SAMPLES:
+                parseCpuSamples(recordLength);
+                return true;
+
+            case UNLOAD_CLASS:
+            case ALLOC_SITES:
+            case HEAP_SUMMARY:
+            case HEAP_DUMP:
+            case HEAP_DUMP_SEGMENT:
+            case HEAP_DUMP_END:
+            default:
+                skipRecord(hprofTag, recordLength);
+                return true;
+        }
+    }
+
+    private void skipRecord(BinaryHprof.Tag hprofTag, long recordLength) throws IOException {
+        if (TRACE) {
+            System.out.println("\tskipping recordLength=" + recordLength);
+        }
+        long skipped = in.skip(recordLength);
+        if (skipped != recordLength) {
+            throw new EOFException("Expected to skip " + recordLength
+                                   + " bytes but only skipped " + skipped + " bytes");
+        }
+    }
+
+    private void parseControlSettings() throws IOException {
+        int flags = in.readInt();
+        short depth = in.readShort();
+        if (TRACE) {
+            System.out.println("\tflags=" + Integer.toHexString(flags));
+            System.out.println("\tdepth=" + depth);
+        }
+        hprofData.setFlags(flags);
+        hprofData.setDepth(depth);
+    }
+
+    private void parseStringInUtf8(int recordLength) throws IOException {
+        int stringId = in.readInt();
+        byte[] bytes = new byte[recordLength - BinaryHprof.ID_SIZE];
+        readFully(in, bytes);
+        String string = new String(bytes, "UTF-8");
+        if (TRACE) {
+            System.out.println("\tstring=" + string);
+        }
+        String old = idToString.put(stringId, string);
+        if (old != null) {
+            throw new MalformedHprofException("Duplicate string id: " + stringId);
+        }
+    }
+
+    private static void readFully(InputStream in, byte[] dst) throws IOException {
+        int offset = 0;
+        int byteCount = dst.length;
+        while (byteCount > 0) {
+            int bytesRead = in.read(dst, offset, byteCount);
+            if (bytesRead < 0) {
+                throw new EOFException();
+            }
+            offset += bytesRead;
+            byteCount -= bytesRead;
+        }
+    }
+
+    private void parseLoadClass() throws IOException {
+        int classId = in.readInt();
+        int classObjectId = readId();
+        // serial number apparently not a stack trace id. (int vs ID)
+        // we don't use this field.
+        int stackTraceSerialNumber = in.readInt();
+        String className = readString();
+        if (TRACE) {
+            System.out.println("\tclassId=" + classId);
+            System.out.println("\tclassObjectId=" + classObjectId);
+            System.out.println("\tstackTraceSerialNumber=" + stackTraceSerialNumber);
+            System.out.println("\tclassName=" + className);
+        }
+        String old = idToClassName.put(classId, className);
+        if (old != null) {
+            throw new MalformedHprofException("Duplicate class id: " + classId);
+        }
+    }
+
+    private int readId() throws IOException {
+        return in.readInt();
+    }
+
+    private String readString() throws IOException {
+        int id = readId();
+        if (id == 0) {
+            return null;
+        }
+        String string = idToString.get(id);
+        if (string == null) {
+            throw new MalformedHprofException("Unknown string id " + id);
+        }
+        return string;
+    }
+
+    private String readClass() throws IOException {
+        int id = readId();
+        String string = idToClassName.get(id);
+        if (string == null) {
+            throw new MalformedHprofException("Unknown class id " + id);
+        }
+        return string;
+    }
+
+    private void parseStartThread() throws IOException {
+        int threadId = in.readInt();
+        int objectId = readId();
+        // stack trace where thread was created.
+        // serial number apparently not a stack trace id. (int vs ID)
+        // we don't use this field.
+        int stackTraceSerialNumber = in.readInt();
+        String threadName = readString();
+        String groupName = readString();
+        String parentGroupName = readString();
+        if (TRACE) {
+            System.out.println("\tthreadId=" + threadId);
+            System.out.println("\tobjectId=" + objectId);
+            System.out.println("\tstackTraceSerialNumber=" + stackTraceSerialNumber);
+            System.out.println("\tthreadName=" + threadName);
+            System.out.println("\tgroupName=" + groupName);
+            System.out.println("\tparentGroupName=" + parentGroupName);
+        }
+        HprofData.ThreadEvent event
+                = HprofData.ThreadEvent.start(objectId, threadId,
+                                              threadName, groupName, parentGroupName);
+        hprofData.addThreadEvent(event);
+    }
+
+    private void parseEndThread() throws IOException {
+        int threadId = in.readInt();
+        if (TRACE) {
+            System.out.println("\tthreadId=" + threadId);
+        }
+        HprofData.ThreadEvent event = HprofData.ThreadEvent.end(threadId);
+        hprofData.addThreadEvent(event);
+    }
+
+    private void parseStackFrame() throws IOException {
+        int stackFrameId = readId();
+        String methodName = readString();
+        String methodSignature = readString();
+        String file = readString();
+        String className = readClass();
+        int line = in.readInt();
+        if (TRACE) {
+            System.out.println("\tstackFrameId=" + stackFrameId);
+            System.out.println("\tclassName=" + className);
+            System.out.println("\tmethodName=" + methodName);
+            System.out.println("\tmethodSignature=" + methodSignature);
+            System.out.println("\tfile=" + file);
+            System.out.println("\tline=" + line);
+        }
+        StackTraceElement stackFrame = new StackTraceElement(className, methodName, file, line);
+        StackTraceElement old = idToStackFrame.put(stackFrameId, stackFrame);
+        if (old != null) {
+            throw new MalformedHprofException("Duplicate stack frame id: " + stackFrameId);
+        }
+    }
+
+    private void parseStackTrace(int recordLength) throws IOException {
+        int stackTraceId = in.readInt();
+        int threadId = in.readInt();
+        int frames = in.readInt();
+        if (TRACE) {
+            System.out.println("\tstackTraceId=" + stackTraceId);
+            System.out.println("\tthreadId=" + threadId);
+            System.out.println("\tframes=" + frames);
+        }
+        int expectedLength = 4 + 4 + 4 + (frames * BinaryHprof.ID_SIZE);
+        if (recordLength != expectedLength) {
+            throw new MalformedHprofException("Expected stack trace record of size "
+                                              + expectedLength
+                                              + " based on number of frames but header "
+                                              + "specified a length of  " + recordLength);
+        }
+        StackTraceElement[] stackFrames = new StackTraceElement[frames];
+        for (int i = 0; i < frames; i++) {
+            int stackFrameId = readId();
+            StackTraceElement stackFrame = idToStackFrame.get(stackFrameId);
+            if (TRACE) {
+                System.out.println("\tstackFrameId=" + stackFrameId);
+                System.out.println("\tstackFrame=" + stackFrame);
+            }
+            if (stackFrame == null) {
+                throw new MalformedHprofException("Unknown stack frame id " + stackFrameId);
+            }
+            stackFrames[i] = stackFrame;
+        }
+
+        HprofData.StackTrace stackTrace
+                = new HprofData.StackTrace(stackTraceId, threadId, stackFrames);
+        if (strict) {
+            hprofData.addStackTrace(stackTrace, new int[1]);
+        } else {
+            // The RI can have duplicate stacks, presumably they
+            // have a minor race if two samples with the same
+            // stack are taken around the same time. if we have a
+            // duplicate, just skip adding it to hprofData, but
+            // register it locally in idToStackFrame. if it seen
+            // in CPU_SAMPLES, we will find a StackTrace is equal
+            // to the first, so they will share a countCell.
+            int[] countCell = stackTraces.get(stackTrace);
+            if (countCell == null) {
+                hprofData.addStackTrace(stackTrace, new int[1]);
+            }
+        }
+
+        HprofData.StackTrace old = idToStackTrace.put(stackTraceId, stackTrace);
+        if (old != null) {
+            throw new MalformedHprofException("Duplicate stack trace id: " + stackTraceId);
+        }
+
+    }
+
+    private void parseCpuSamples(int recordLength) throws IOException {
+        int totalSamples = in.readInt();
+        int samplesCount = in.readInt();
+        if (TRACE) {
+            System.out.println("\ttotalSamples=" + totalSamples);
+            System.out.println("\tsamplesCount=" + samplesCount);
+        }
+        int expectedLength = 4 + 4 + (samplesCount * (4 + 4));
+        if (recordLength != expectedLength) {
+            throw new MalformedHprofException("Expected CPU samples record of size "
+                                              + expectedLength
+                                              + " based on number of samples but header "
+                                              + "specified a length of  " + recordLength);
+        }
+        int total = 0;
+        for (int i = 0; i < samplesCount; i++) {
+            int count = in.readInt();
+            int stackTraceId = in.readInt();
+            if (TRACE) {
+                System.out.println("\tcount=" + count);
+                System.out.println("\tstackTraceId=" + stackTraceId);
+            }
+            HprofData.StackTrace stackTrace = idToStackTrace.get(stackTraceId);
+            if (stackTrace == null) {
+                throw new MalformedHprofException("Unknown stack trace id " + stackTraceId);
+            }
+            if (count == 0) {
+                throw new MalformedHprofException("Zero sample count for stack trace "
+                                                  + stackTrace);
+            }
+            int[] countCell = stackTraces.get(stackTrace);
+            if (strict) {
+                if (countCell[0] != 0) {
+                    throw new MalformedHprofException("Setting sample count of stack trace "
+                                                      + stackTrace + " to " + count
+                                                      + " found it was already initialized to "
+                                                      + countCell[0]);
+                }
+            } else {
+                // Coalesce counts from duplicate stack traces.
+                // For more on this, see comments in parseStackTrace.
+                count += countCell[0];
+            }
+            countCell[0] = count;
+            total += count;
+        }
+        if (strict && totalSamples != total) {
+            throw new MalformedHprofException("Expected a total of " + totalSamples
+                                              + " samples but saw " + total);
+        }
+    }
+}
diff --git a/dalvik/src/main/java/dalvik/system/profiler/BinaryHprofWriter.java b/dalvik/src/main/java/dalvik/system/profiler/BinaryHprofWriter.java
new file mode 100644
index 0000000..808572d
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/BinaryHprofWriter.java
@@ -0,0 +1,245 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+public final class BinaryHprofWriter implements HprofWriter {
+
+    private int nextStringId = 1; // id 0 => null
+    private int nextClassId = 1;
+    private int nextStackFrameId = 1;
+    private final Map<String, Integer> stringToId = new HashMap<String, Integer>();
+    private final Map<String, Integer> classNameToId = new HashMap<String, Integer>();
+    private final Map<StackTraceElement, Integer> stackFrameToId
+            = new HashMap<StackTraceElement, Integer>();
+
+    private final HprofData data;
+    private final DataOutputStream out;
+
+    public BinaryHprofWriter(HprofData data, OutputStream outputStream) {
+        this.data = data;
+        this.out = new DataOutputStream(outputStream);
+    }
+
+    public void write() throws IOException {
+        try {
+            writeHeader(data.getStartMillis());
+
+            writeControlSettings(data.getFlags(), data.getDepth());
+
+            for (HprofData.ThreadEvent event : data.getThreadHistory()) {
+                writeThreadEvent(event);
+            }
+
+            Set<HprofData.Sample> samples = data.getSamples();
+            int total = 0;
+            for (HprofData.Sample sample : samples) {
+                total += sample.count;
+                writeStackTrace(sample.stackTrace);
+            }
+            writeCpuSamples(total, samples);
+
+        } finally {
+            out.flush();
+        }
+    }
+
+    private void writeHeader(long dumpTimeInMilliseconds) throws IOException {
+        out.writeBytes("JAVA PROFILE 1.0.2");
+        out.writeByte(0); // null terminated string
+        out.writeInt(BinaryHprof.ID_SIZE);
+        out.writeLong(dumpTimeInMilliseconds);
+    }
+
+    private void writeControlSettings(int flags, int depth) throws IOException {
+        if (depth > Short.MAX_VALUE) {
+            throw new IllegalArgumentException("depth too large for binary hprof: "
+                                               + depth + " > " + Short.MAX_VALUE);
+        }
+        writeRecordHeader(BinaryHprof.Tag.CONTROL_SETTINGS,
+                          0,
+                          BinaryHprof.Tag.CONTROL_SETTINGS.maximumSize);
+        out.writeInt(flags);
+        out.writeShort((short) depth);
+    }
+
+    private void writeThreadEvent(HprofData.ThreadEvent e) throws IOException {
+        switch (e.type) {
+            case START:
+                writeStartThread(e);
+                return;
+            case END:
+                writeStopThread(e);
+                return;
+        }
+        throw new IllegalStateException(e.type.toString());
+    }
+
+    private void writeStartThread(HprofData.ThreadEvent e) throws IOException {
+        int threadNameId = writeString(e.threadName);
+        int groupNameId = writeString(e.groupName);
+        int parentGroupNameId = writeString(e.parentGroupName);
+        writeRecordHeader(BinaryHprof.Tag.START_THREAD,
+                          0,
+                          BinaryHprof.Tag.START_THREAD.maximumSize);
+        out.writeInt(e.threadId);
+        writeId(e.objectId);
+        out.writeInt(0); // stack trace where thread was started unavailable
+        writeId(threadNameId);
+        writeId(groupNameId);
+        writeId(parentGroupNameId);
+    }
+
+    private void writeStopThread(HprofData.ThreadEvent e) throws IOException {
+        writeRecordHeader(BinaryHprof.Tag.END_THREAD,
+                          0,
+                          BinaryHprof.Tag.END_THREAD.maximumSize);
+        out.writeInt(e.threadId);
+    }
+
+    private void writeRecordHeader(BinaryHprof.Tag hprofTag,
+                                   int timeDeltaInMicroseconds,
+                                   int recordLength) throws IOException {
+        String error = hprofTag.checkSize(recordLength);
+        if (error != null) {
+            throw new AssertionError(error);
+        }
+        out.writeByte(hprofTag.tag);
+        out.writeInt(timeDeltaInMicroseconds);
+        out.writeInt(recordLength);
+    }
+
+    private void writeId(int id) throws IOException {
+        out.writeInt(id);
+    }
+
+    /**
+     * Ensures that a string has been writen to the out and
+     * returns its ID. The ID of a null string is zero, and
+     * doesn't actually result in any output. In a string has
+     * already been written previously, the earlier ID will be
+     * returned and no output will be written.
+     */
+    private int writeString(String string) throws IOException {
+        if (string == null) {
+            return 0;
+        }
+        Integer identifier = stringToId.get(string);
+        if (identifier != null) {
+            return identifier;
+        }
+
+        int id = nextStringId++;
+        stringToId.put(string, id);
+
+        byte[] bytes = string.getBytes("UTF-8");
+        writeRecordHeader(BinaryHprof.Tag.STRING_IN_UTF8,
+                          0,
+                          BinaryHprof.ID_SIZE + bytes.length);
+        out.writeInt(id);
+        out.write(bytes, 0, bytes.length);
+
+        return id;
+    }
+
+    private void writeCpuSamples(int totalSamples, Set<HprofData.Sample> samples)
+            throws IOException {
+        int samplesCount = samples.size();
+        if (samplesCount == 0) {
+            return;
+        }
+        writeRecordHeader(BinaryHprof.Tag.CPU_SAMPLES, 0, 4 + 4 + (samplesCount * (4 + 4)));
+        out.writeInt(totalSamples);
+        out.writeInt(samplesCount);
+        for (HprofData.Sample sample : samples) {
+            out.writeInt(sample.count);
+            out.writeInt(sample.stackTrace.stackTraceId);
+        }
+    }
+
+    private void writeStackTrace(HprofData.StackTrace stackTrace) throws IOException {
+        int frames = stackTrace.stackFrames.length;
+        int[] stackFrameIds = new int[frames];
+        for (int i = 0; i < frames; i++) {
+            stackFrameIds[i] = writeStackFrame(stackTrace.stackFrames[i]);
+        }
+        writeRecordHeader(BinaryHprof.Tag.STACK_TRACE,
+                          0,
+                          4 + 4 + 4 + (frames * BinaryHprof.ID_SIZE));
+        out.writeInt(stackTrace.stackTraceId);
+        out.writeInt(stackTrace.threadId);
+        out.writeInt(frames);
+        for (int stackFrameId : stackFrameIds) {
+            writeId(stackFrameId);
+        }
+    }
+
+    private int writeLoadClass(String className) throws IOException {
+        Integer identifier = classNameToId.get(className);
+        if (identifier != null) {
+            return identifier;
+        }
+        int id = nextClassId++;
+        classNameToId.put(className, id);
+
+        int classNameId = writeString(className);
+        writeRecordHeader(BinaryHprof.Tag.LOAD_CLASS,
+                          0,
+                          BinaryHprof.Tag.LOAD_CLASS.maximumSize);
+        out.writeInt(id);
+        writeId(0); // class object ID
+        out.writeInt(0); // stack trace where class was loaded is unavailable
+        writeId(classNameId);
+
+        return id;
+    }
+
+    private int writeStackFrame(StackTraceElement stackFrame) throws IOException {
+        Integer identifier = stackFrameToId.get(stackFrame);
+        if (identifier != null) {
+            return identifier;
+        }
+
+        int id = nextStackFrameId++;
+        stackFrameToId.put(stackFrame, id);
+
+        int classId = writeLoadClass(stackFrame.getClassName());
+        int methodNameId = writeString(stackFrame.getMethodName());
+        int sourceId = writeString(stackFrame.getFileName());
+        writeRecordHeader(BinaryHprof.Tag.STACK_FRAME,
+                          0,
+                          BinaryHprof.Tag.STACK_FRAME.maximumSize);
+        writeId(id);
+        writeId(methodNameId);
+        writeId(0); // method signature is unavailable from StackTraceElement
+        writeId(sourceId);
+        out.writeInt(classId);
+        out.writeInt(stackFrame.getLineNumber());
+
+        return id;
+    }
+
+    public void close() throws IOException {
+        out.close();
+    }
+}
diff --git a/dalvik/src/main/java/dalvik/system/profiler/HprofBinaryToAscii.java b/dalvik/src/main/java/dalvik/system/profiler/HprofBinaryToAscii.java
new file mode 100644
index 0000000..2fed9d8
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/HprofBinaryToAscii.java
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.io.BufferedInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * Run on device with:
+ * adb shell dalvikvm 'dalvik.system.SamplingProfiler\$HprofBinaryToAscii'
+ *
+ * Run on host with:
+ * java -classpath out/target/common/obj/JAVA_LIBRARIES/core_intermediates/classes.jar
+ */
+public final class HprofBinaryToAscii {
+
+    public static void main(String[] args) {
+        System.exit(convert(args) ? 0 : 1);
+    }
+
+    public static boolean convert(String[] args) {
+
+        if (args.length != 1) {
+            usage("binary hprof file argument expected");
+            return false;
+        }
+        File file = new File(args[0]);
+        if (!file.exists()) {
+            usage("file " + file + " does not exist");
+            return false;
+        }
+
+        HprofData hprofData;
+        InputStream inputStream = null;
+        try {
+            inputStream = new BufferedInputStream(new FileInputStream(file));
+            BinaryHprofReader reader = new BinaryHprofReader(inputStream);
+            reader.setStrict(false);
+            reader.read();
+            hprofData = reader.getHprofData();
+        } catch (IOException e) {
+            System.out.println("Problem reading binary hprof data from "
+                               + file + ": " + e.getMessage());
+            return false;
+        } finally {
+            if (inputStream != null) {
+                try {
+                    inputStream.close();
+                } catch (IOException ignored) {
+                }
+            }
+        }
+        try {
+            HprofWriter writer = new AsciiHprofWriter(hprofData, System.out);
+            writer.write();
+        } catch (IOException e) {
+            System.out.println("Problem writing ASCII hprof data: " + e.getMessage());
+            return false;
+        }
+        return true;
+    }
+
+    private static void usage(String error) {
+        System.out.print("ERROR: ");
+        System.out.println(error);
+        System.out.println();
+        System.out.println("usage: HprofBinaryToAscii <binary-hprof-file>");
+        System.out.println();
+        System.out.println("Reads a binary hprof file and print it in ASCII format");
+    }
+}
diff --git a/dalvik/src/main/java/dalvik/system/profiler/HprofData.java b/dalvik/src/main/java/dalvik/system/profiler/HprofData.java
new file mode 100644
index 0000000..7b44bb9
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/HprofData.java
@@ -0,0 +1,394 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map.Entry;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Represents sampling profiler data. Can be converted to ASCII or
+ * binary hprof-style output using {@link AsciiHprofWriter} or
+ * {@link BinaryHprofWriter}.
+ * <p>
+ * The data includes:
+ * <ul>
+ * <li>the start time of the last sampling period
+ * <li>the history of thread start and end events
+ * <li>stack traces with frequency counts
+ * <ul>
+ */
+public final class HprofData {
+
+    public static enum ThreadEventType { START, END };
+
+    /**
+     * ThreadEvent represents thread creation and death events for
+     * reporting. It provides a record of the thread and thread group
+     * names for tying samples back to their source thread.
+     */
+    public static final class ThreadEvent {
+
+        public final ThreadEventType type;
+        public final int objectId;
+        public final int threadId;
+        public final String threadName;
+        public final String groupName;
+        public final String parentGroupName;
+
+        public static ThreadEvent start(int objectId, int threadId, String threadName,
+                                        String groupName, String parentGroupName) {
+            return new ThreadEvent(ThreadEventType.START, objectId, threadId,
+                                   threadName, groupName, parentGroupName);
+        }
+
+        public static ThreadEvent end(int threadId) {
+            return new ThreadEvent(ThreadEventType.END, threadId);
+        }
+
+        private ThreadEvent(ThreadEventType type, int objectId, int threadId,
+                            String threadName, String groupName, String parentGroupName) {
+            if (threadName == null) {
+                throw new NullPointerException("threadName == null");
+            }
+            this.type = ThreadEventType.START;
+            this.objectId = objectId;
+            this.threadId = threadId;
+            this.threadName = threadName;
+            this.groupName = groupName;
+            this.parentGroupName = parentGroupName;
+        }
+
+        private ThreadEvent(ThreadEventType type, int threadId) {
+            this.type = ThreadEventType.END;
+            this.objectId = -1;
+            this.threadId = threadId;
+            this.threadName = null;
+            this.groupName = null;
+            this.parentGroupName = null;
+        }
+
+        @Override public int hashCode() {
+            int result = 17;
+            result = 31 * result + objectId;
+            result = 31 * result + threadId;
+            result = 31 * result + hashCode(threadName);
+            result = 31 * result + hashCode(groupName);
+            result = 31 * result + hashCode(parentGroupName);
+            return result;
+        }
+
+        private static int hashCode(Object o) {
+            return (o == null) ? 0 : o.hashCode();
+        }
+
+        @Override public boolean equals(Object o) {
+            if (!(o instanceof ThreadEvent)) {
+                return false;
+            }
+            ThreadEvent event = (ThreadEvent) o;
+            return (this.type == event.type
+                    && this.objectId == event.objectId
+                    && this.threadId == event.threadId
+                    && equal(this.threadName, event.threadName)
+                    && equal(this.groupName, event.groupName)
+                    && equal(this.parentGroupName, event.parentGroupName));
+        }
+
+        private static boolean equal(Object a, Object b) {
+            return a == b || (a != null && a.equals(b));
+        }
+
+        @Override public String toString() {
+            switch (type) {
+                case START:
+                    return String.format(
+                            "THREAD START (obj=%d, id = %d, name=\"%s\", group=\"%s\")",
+                            objectId, threadId, threadName, groupName);
+                case END:
+                    return String.format("THREAD END (id = %d)", threadId);
+            }
+            throw new IllegalStateException(type.toString());
+        }
+    }
+
+    /**
+     * A unique stack trace for a specific thread.
+     */
+    public static final class StackTrace {
+
+        public final int stackTraceId;
+        int threadId;
+        StackTraceElement[] stackFrames;
+
+        StackTrace() {
+            this.stackTraceId = -1;
+        }
+
+        public StackTrace(int stackTraceId, int threadId, StackTraceElement[] stackFrames) {
+            if (stackFrames == null) {
+                throw new NullPointerException("stackFrames == null");
+            }
+            this.stackTraceId = stackTraceId;
+            this.threadId = threadId;
+            this.stackFrames = stackFrames;
+        }
+
+        public int getThreadId() {
+            return threadId;
+        }
+
+        public StackTraceElement[] getStackFrames() {
+            return stackFrames;
+        }
+
+        @Override public int hashCode() {
+            int result = 17;
+            result = 31 * result + threadId;
+            result = 31 * result + Arrays.hashCode(stackFrames);
+            return result;
+        }
+
+        @Override public boolean equals(Object o) {
+            if (!(o instanceof StackTrace)) {
+                return false;
+            }
+            StackTrace s = (StackTrace) o;
+            return threadId == s.threadId && Arrays.equals(stackFrames, s.stackFrames);
+        }
+
+        @Override public String toString() {
+            StringBuilder frames = new StringBuilder();
+            if (stackFrames.length > 0) {
+                frames.append('\n');
+                for (StackTraceElement stackFrame : stackFrames) {
+                    frames.append("\t at ");
+                    frames.append(stackFrame);
+                    frames.append('\n');
+                }
+            } else {
+                frames.append("<empty>");
+            }
+            return "StackTrace[stackTraceId=" + stackTraceId
+                    + ", threadId=" + threadId
+                    + ", frames=" + frames + "]";
+
+        }
+    }
+
+    /**
+     * A read only container combining a stack trace with its frequency.
+     */
+    public static final class Sample {
+
+        public final StackTrace stackTrace;
+        public final int count;
+
+        private Sample(StackTrace stackTrace, int count) {
+            if (stackTrace == null) {
+                throw new NullPointerException("stackTrace == null");
+            }
+            if (count < 0) {
+                throw new IllegalArgumentException("count < 0:" + count);
+            }
+            this.stackTrace = stackTrace;
+            this.count = count;
+        }
+
+        @Override public int hashCode() {
+            int result = 17;
+            result = 31 * result + stackTrace.hashCode();
+            result = 31 * result + count;
+            return result;
+        }
+
+        @Override public boolean equals(Object o) {
+            if (!(o instanceof Sample)) {
+                return false;
+            }
+            Sample s = (Sample) o;
+            return count == s.count && stackTrace.equals(s.stackTrace);
+        }
+
+        @Override public String toString() {
+            return "Sample[count=" + count + " " + stackTrace + "]";
+        }
+
+    }
+
+    /**
+     * Start of last sampling period.
+     */
+    private long startMillis;
+
+    /**
+     * CONTROL_SETTINGS flags
+     */
+    private int flags;
+
+    /**
+     * stack sampling depth
+     */
+    private int depth;
+
+    /**
+     * List of thread creation and death events.
+     */
+    private final List<ThreadEvent> threadHistory = new ArrayList<ThreadEvent>();
+
+    /**
+     * Map of thread id to a start ThreadEvent
+     */
+    private final Map<Integer, ThreadEvent> threadIdToThreadEvent
+            = new HashMap<Integer, ThreadEvent>();
+
+    /**
+     * Map of stack traces to a mutable sample count. The map is
+     * provided by the creator of the HprofData so only have
+     * mutable access to the int[] cells that contain the sample
+     * count. Only an unmodifiable iterator view is available to
+     * users of the HprofData.
+     */
+    private final Map<HprofData.StackTrace, int[]> stackTraces;
+
+    public HprofData(Map<StackTrace, int[]> stackTraces) {
+        if (stackTraces == null) {
+            throw new NullPointerException("stackTraces == null");
+        }
+        this.stackTraces = stackTraces;
+    }
+
+    /**
+     * The start time in milliseconds of the last profiling period.
+     */
+    public long getStartMillis() {
+        return startMillis;
+    }
+
+    /**
+     * Set the time for the start of the current sampling period.
+     */
+    public void setStartMillis(long startMillis) {
+        this.startMillis = startMillis;
+    }
+
+    /**
+     * Get the {@link BinaryHprof.ControlSettings} flags
+     */
+    public int getFlags() {
+        return flags;
+    }
+
+    /**
+     * Set the {@link BinaryHprof.ControlSettings} flags
+     */
+    public void setFlags(int flags) {
+        this.flags = flags;
+    }
+
+    /**
+     * Get the stack sampling depth
+     */
+    public int getDepth() {
+        return depth;
+    }
+
+    /**
+     * Set the stack sampling depth
+     */
+    public void setDepth(int depth) {
+        this.depth = depth;
+    }
+
+    /**
+     * Return an unmodifiable history of start and end thread events.
+     */
+    public List<ThreadEvent> getThreadHistory() {
+        return Collections.unmodifiableList(threadHistory);
+    }
+
+    /**
+     * Return a new set containing the current sample data.
+     */
+    public Set<Sample> getSamples() {
+        Set<Sample> samples = new HashSet<Sample>(stackTraces.size());
+        for (Entry<StackTrace, int[]> e : stackTraces.entrySet()) {
+            StackTrace stackTrace = e.getKey();
+            int countCell[] = e.getValue();
+            int count = countCell[0];
+            Sample sample = new Sample(stackTrace, count);
+            samples.add(sample);
+        }
+        return samples;
+    }
+
+    /**
+     * Record an event in the thread history.
+     */
+    public void addThreadEvent(ThreadEvent event) {
+        if (event == null) {
+            throw new NullPointerException("event == null");
+        }
+        ThreadEvent old = threadIdToThreadEvent.put(event.threadId, event);
+        switch (event.type) {
+            case START:
+                if (old != null) {
+                    throw new IllegalArgumentException("ThreadEvent already registered for id "
+                                                       + event.threadId);
+                }
+                break;
+            case END:
+                // Do not assert that the END_THREAD matches a
+                // START_THREAD unless in strict mode. While thhis
+                // hold true in the binary hprof BinaryHprofWriter
+                // produces, it is not true of hprof files created
+                // by the RI. However, if there is an event
+                // already registed for a thread id, it should be
+                // the matching start, not a duplicate end.
+                if (old != null && old.type == ThreadEventType.END) {
+                    throw new IllegalArgumentException("Duplicate ThreadEvent.end for id "
+                                                       + event.threadId);
+                }
+                break;
+        }
+        threadHistory.add(event);
+    }
+
+    /**
+     * Record an stack trace and an associated int[] cell of
+     * sample cound for the stack trace. The caller is allowed
+     * retain a pointer to the cell to update the count. The
+     * SamplingProfiler intentionally does not present a mutable
+     * view of the count.
+     */
+    public void addStackTrace(StackTrace stackTrace, int[] countCell) {
+        if (!threadIdToThreadEvent.containsKey(stackTrace.threadId)) {
+            throw new IllegalArgumentException("Unknown thread id " + stackTrace.threadId);
+        }
+        int[] old = stackTraces.put(stackTrace, countCell);
+        if (old != null) {
+            throw new IllegalArgumentException("StackTrace already registered for id "
+                                               + stackTrace.stackTraceId + ":\n" + stackTrace);
+        }
+    }
+}
diff --git a/dalvik/src/main/java/dalvik/system/profiler/HprofWriter.java b/dalvik/src/main/java/dalvik/system/profiler/HprofWriter.java
new file mode 100644
index 0000000..b1d5a9b
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/HprofWriter.java
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.io.IOException;
+
+public interface HprofWriter {
+    public void write() throws IOException;
+}
diff --git a/dalvik/src/main/java/dalvik/system/profiler/MalformedHprofException.java b/dalvik/src/main/java/dalvik/system/profiler/MalformedHprofException.java
new file mode 100644
index 0000000..b4097b2
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/MalformedHprofException.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.io.IOException;
+
+public final class MalformedHprofException extends IOException {
+
+    private static final long serialVersionUID = 8558990237047894213L;
+
+    MalformedHprofException(String message) {
+        super(message);
+    }
+    MalformedHprofException(String message, Throwable cause) {
+        super(message, cause);
+    }
+    MalformedHprofException(Throwable cause) {
+        super(cause);
+    }
+}
+
diff --git a/dalvik/src/main/java/dalvik/system/profiler/SamplingProfiler.java b/dalvik/src/main/java/dalvik/system/profiler/SamplingProfiler.java
new file mode 100644
index 0000000..13421ec
--- /dev/null
+++ b/dalvik/src/main/java/dalvik/system/profiler/SamplingProfiler.java
@@ -0,0 +1,443 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dalvik.system.profiler;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.Timer;
+import java.util.TimerTask;
+
+/**
+ * A sampling profiler. It currently is implemented without any
+ * virtual machine support, relying solely on {@code
+ * Thread.getStackTrace} to collect samples. As such, the overhead is
+ * higher than a native approach and it does not provide insight into
+ * where time is spent within native code, but it can still provide
+ * useful insight into where a program is spending time.
+ *
+ * <h3>Usage Example</h3>
+ *
+ * The following example shows how to use the {@code
+ * SamplingProfiler}. It samples the current thread's stack to a depth
+ * of 12 stack frame elements over two different measurement periods
+ * with samples taken every 100 milliseconds. In then prints the
+ * results in hprof format to the standard output.
+ *
+ * <pre> {@code
+ * ThreadSet threadSet = SamplingProfiler.newArrayThreadSet(Thread.currentThread());
+ * SamplingProfiler profiler = new SamplingProfiler(12, threadSet);
+ * profiler.start(100);
+ * // period of measurement
+ * profiler.stop();
+ * // period of non-measurement
+ * profiler.start(100);
+ * // another period of measurement
+ * profiler.stop();
+ * profiler.shutdown();
+ * HprofWriter writer = new AsciiHprofWriter(profiler.getHprofData(), System.out);
+ * writer.write();
+ * }</pre>
+ */
+public final class SamplingProfiler {
+
+    /**
+     * Map of stack traces to a mutable sample count.
+     */
+    private final Map<HprofData.StackTrace, int[]> stackTraces
+            = new HashMap<HprofData.StackTrace, int[]>();
+
+    /**
+     * Data collected by the sampling profiler
+     */
+    private final HprofData hprofData = new HprofData(stackTraces);
+
+    /**
+     * Timer that is used for the lifetime of the profiler
+     */
+    private final Timer timer = new Timer("SamplingProfiler", true);
+
+    /**
+     * A sampler is created every time profiling starts and cleared
+     * everytime profiling stops because once a {@code TimerTask} is
+     * canceled it cannot be reused.
+     */
+    private TimerTask sampler;
+
+    /**
+     * The maximum number of {@code StackTraceElements} to retain in
+     * each stack.
+     */
+    private final int depth;
+
+    /**
+     * The {@code ThreadSet} that identifies which threads to sample.
+     */
+    private final ThreadSet threadSet;
+
+    /*
+     *  Real hprof output examples don't start the thread and trace
+     *  identifiers at one but seem to start at these arbitrary
+     *  constants. It certainly seems useful to have relatively unique
+     *  identifers when manual searching hprof output.
+     */
+    private int nextThreadId = 200001;
+    private int nextStackTraceId = 300001;
+    private int nextObjectId = 1;
+
+    /**
+     * The threads currently known to the profiler for detecting
+     * thread start and end events.
+     */
+    private Thread[] currentThreads = new Thread[0];
+
+    /**
+     * Map of currently active threads to their identifiers. When
+     * threads disappear they are removed and only referenced by their
+     * identifiers to prevent retaining garbage threads.
+     */
+    private final Map<Thread, Integer> threadIds = new HashMap<Thread, Integer>();
+
+    /**
+     * Mutable StackTrace that is used for probing stackTraces Map
+     * without allocating a StackTrace. If addStackTrace needs to
+     * be thread safe, this would need to be reconsidered.
+     */
+    private final HprofData.StackTrace mutableStackTrace = new HprofData.StackTrace();
+
+    /**
+     * Create a sampling profiler that collects stacks with the
+     * specified depth from the threads specified by the specified
+     * thread collector.
+     *
+     * @param depth The maximum stack depth to retain for each sample
+     * similar to the hprof option of the same name. Any stack deeper
+     * than this will be truncated to this depth. A good starting
+     * value is 4 although it is not uncommon to need to raise this to
+     * get enough context to understand program behavior. While
+     * programs with extensive recursion may require a high value for
+     * depth, simply passing in a value for Integer.MAX_VALUE is not
+     * advised because of the significant memory need to retain such
+     * stacks and runtime overhead to compare stacks.
+     */
+    public SamplingProfiler(int depth, ThreadSet threadSet) {
+        this.depth = depth;
+        this.threadSet = threadSet;
+        hprofData.setFlags(BinaryHprof.ControlSettings.CPU_SAMPLING.bitmask);
+        hprofData.setDepth(depth);
+    }
+
+    /**
+     * A ThreadSet specifies the set of threads to sample.
+     */
+    public static interface ThreadSet {
+        /**
+         * Returns an array containing the threads to be sampled. The
+         * array may be longer than the number of threads to be
+         * sampled, in which case the extra elements must be null.
+         */
+        public Thread[] threads();
+    }
+
+    /**
+     * Returns a ThreadSet for a fixed set of threads that will not
+     * vary at runtime. This has less overhead than a dynamically
+     * calculated set, such as {@link #newThreadGroupTheadSet}, which has
+     * to enumerate the threads each time profiler wants to collect
+     * samples.
+     */
+    public static ThreadSet newArrayThreadSet(Thread... threads) {
+        return new ArrayThreadSet(threads);
+    }
+
+    /**
+     * An ArrayThreadSet samples a fixed set of threads that does not
+     * vary over the life of the profiler.
+     */
+    private static class ArrayThreadSet implements ThreadSet {
+        private final Thread[] threads;
+        public ArrayThreadSet(Thread... threads) {
+            if (threads == null) {
+                throw new NullPointerException("threads == null");
+            }
+            this.threads = threads;
+        }
+        public Thread[] threads() {
+            return threads;
+        }
+    }
+
+    /**
+     * Returns a ThreadSet that is dynamically computed based on the
+     * threads found in the specified ThreadGroup and that
+     * ThreadGroup's children.
+     */
+    public static ThreadSet newThreadGroupTheadSet(ThreadGroup threadGroup) {
+        return new ThreadGroupThreadSet(threadGroup);
+    }
+
+    /**
+     * An ThreadGroupThreadSet sample the threads from the specified
+     * ThreadGroup and the ThreadGroup's children
+     */
+    private static class ThreadGroupThreadSet implements ThreadSet {
+        private final ThreadGroup threadGroup;
+        private Thread[] threads;
+        private int lastThread;
+
+        public ThreadGroupThreadSet(ThreadGroup threadGroup) {
+            if (threadGroup == null) {
+                throw new NullPointerException("threadGroup == null");
+            }
+            this.threadGroup = threadGroup;
+            resize();
+        }
+
+        private void resize() {
+            int count = threadGroup.activeCount();
+            // we can only tell if we had enough room for all active
+            // threads if we actually are larger than the the number of
+            // active threads. making it larger also leaves us room to
+            // tolerate additional threads without resizing.
+            threads = new Thread[count*2];
+            lastThread = 0;
+        }
+
+        public Thread[] threads() {
+            int threadCount;
+            while (true) {
+                threadCount = threadGroup.enumerate(threads);
+                if (threadCount == threads.length) {
+                    resize();
+                } else {
+                    break;
+                }
+            }
+            if (threadCount < lastThread) {
+                // avoid retaining pointers to threads that have ended
+                Arrays.fill(threads, threadCount, lastThread, null);
+            }
+            lastThread = threadCount;
+            return threads;
+        }
+    }
+
+    /**
+     * Starts profiler sampling at the specified rate.
+     *
+     * @param interval The number of milliseconds between samples
+     */
+    public void start(int interval) {
+        if (interval < 1) {
+            throw new IllegalArgumentException("interval < 1");
+        }
+        if (sampler != null) {
+            throw new IllegalStateException("profiling already started");
+        }
+        sampler = new Sampler();
+        hprofData.setStartMillis(System.currentTimeMillis());
+        timer.scheduleAtFixedRate(sampler, 0, interval);
+    }
+
+    /**
+     * Stops profiler sampling. It can be restarted with {@link
+     * #start(int)} to continue sampling.
+     */
+    public void stop() {
+        if (sampler == null) {
+            return;
+        }
+        sampler.cancel();
+        sampler = null;
+    }
+
+    /**
+     * Shuts down profiling after which it can not be restarted. It is
+     * important to shut down profiling when done to free resources
+     * used by the profiler. Shutting down the profiler also stops the
+     * profiling if that has not already been done.
+     */
+    public void shutdown() {
+        stop();
+        timer.cancel();
+    }
+
+    /**
+     * Returns the hprof data accumulated by the profiler since it was
+     * created. The profiler needs to be stopped, but not necessarily
+     * shut down, in order to access the data. If the profiler is
+     * restarted, there is no thread safe way to access the data.
+     */
+    public HprofData getHprofData() {
+        if (sampler != null) {
+            throw new IllegalStateException("cannot access hprof data while sampling");
+        }
+        return hprofData;
+    }
+
+    /**
+     * The Sampler does the real work of the profiler.
+     *
+     * At every sample time, it asks the thread set for the set
+     * of threads to sample. It maintains a history of thread creation
+     * and death events based on changes observed to the threads
+     * returned by the {@code ThreadSet}.
+     *
+     * For each thread to be sampled, a stack is collected and used to
+     * update the set of collected samples. Stacks are truncated to a
+     * maximum depth. There is no way to tell if a stack has been truncated.
+     */
+    private class Sampler extends TimerTask {
+
+        private Thread timerThread;
+
+        public void run() {
+            if (timerThread == null) {
+                timerThread = Thread.currentThread();
+            }
+
+            // process thread creation and death first so that we
+            // assign thread ids to any new threads before allocating
+            // new stacks for them
+            Thread[] newThreads = threadSet.threads();
+            if (!Arrays.equals(currentThreads, newThreads)) {
+                updateThreadHistory(currentThreads, newThreads);
+                currentThreads = newThreads.clone();
+            }
+
+            for (Thread thread : currentThreads) {
+                if (thread == null) {
+                    break;
+                }
+                if (thread == timerThread) {
+                    continue;
+                }
+
+                // TODO replace with a VMStack.getThreadStackTrace
+                // variant to avoid allocating unneeded elements
+                StackTraceElement[] stackFrames = thread.getStackTrace();
+                if (stackFrames.length == 0) {
+                    continue;
+                }
+                if (stackFrames.length > depth) {
+                    stackFrames = Arrays.copyOfRange(stackFrames, 0, depth);
+                }
+                recordStackTrace(thread, stackFrames);
+            }
+        }
+
+        /**
+         * Record a new stack trace. The thread should have been
+         * previously registered with addStartThread.
+         */
+        private void recordStackTrace(Thread thread, StackTraceElement[] stackFrames) {
+            Integer threadId = threadIds.get(thread);
+            if (threadId == null) {
+                throw new IllegalArgumentException("Unknown thread " + thread);
+            }
+            mutableStackTrace.threadId = threadId;
+            mutableStackTrace.stackFrames = stackFrames;
+
+            int[] countCell = stackTraces.get(mutableStackTrace);
+            if (countCell == null) {
+                countCell = new int[1];
+                HprofData.StackTrace stackTrace
+                        = new HprofData.StackTrace(nextStackTraceId++, threadId, stackFrames);
+                hprofData.addStackTrace(stackTrace, countCell);
+            }
+            countCell[0]++;
+        }
+
+        private void updateThreadHistory(Thread[] oldThreads, Thread[] newThreads) {
+            // thread start/stop shouldn't happen too often and
+            // these aren't too big, so hopefully this approach
+            // won't be too slow...
+            Set<Thread> n = new HashSet<Thread>(Arrays.asList(newThreads));
+            Set<Thread> o = new HashSet<Thread>(Arrays.asList(oldThreads));
+
+            // added = new-old
+            Set<Thread> added = new HashSet<Thread>(n);
+            added.removeAll(o);
+
+            // removed = old-new
+            Set<Thread> removed = new HashSet<Thread>(o);
+            removed.removeAll(n);
+
+            for (Thread thread : added) {
+                if (thread == null) {
+                    continue;
+                }
+                if (thread == timerThread) {
+                    continue;
+                }
+                addStartThread(thread);
+            }
+            for (Thread thread : removed) {
+                if (thread == null) {
+                    continue;
+                }
+                if (thread == timerThread) {
+                    continue;
+                }
+                addEndThread(thread);
+            }
+        }
+
+        /**
+         * Record that a newly noticed thread.
+         */
+        private void addStartThread(Thread thread) {
+            if (thread == null) {
+                throw new NullPointerException("thread == null");
+            }
+            int threadId = nextThreadId++;
+            Integer old = threadIds.put(thread, threadId);
+            if (old != null) {
+                throw new IllegalArgumentException("Thread already registered as " + old);
+            }
+
+            String threadName = thread.getName();
+            // group will become null when thread is terminated
+            ThreadGroup group = thread.getThreadGroup();
+            String groupName = group == null ? null : group.getName();
+            ThreadGroup parentGroup = group == null ? null : group.getParent();
+            String parentGroupName = parentGroup == null ? null : parentGroup.getName();
+
+            HprofData.ThreadEvent event
+                    = HprofData.ThreadEvent.start(nextObjectId++, threadId,
+                                                  threadName, groupName, parentGroupName);
+            hprofData.addThreadEvent(event);
+        }
+
+        /**
+         * Record that a thread has disappeared.
+         */
+        private void addEndThread(Thread thread) {
+            if (thread == null) {
+                throw new NullPointerException("thread == null");
+            }
+            Integer threadId = threadIds.remove(thread);
+            if (threadId == null) {
+                throw new IllegalArgumentException("Unknown thread " + thread);
+            }
+            HprofData.ThreadEvent event = HprofData.ThreadEvent.end(threadId);
+            hprofData.addThreadEvent(event);
+        }
+    }
+}
diff --git a/dalvik/src/test/java/dalvik/system/SamplingProfilerTest.java b/dalvik/src/test/java/dalvik/system/profiler/SamplingProfilerTest.java
index c132d94..6a43aad 100644
--- a/dalvik/src/test/java/dalvik/system/SamplingProfilerTest.java
+++ b/dalvik/src/test/java/dalvik/system/profiler/SamplingProfilerTest.java
@@ -14,17 +14,17 @@
  * limitations under the License.
  */
 
-package dalvik.system;
-
-import dalvik.system.SamplingProfiler.AsciiHprofWriter;
-import dalvik.system.SamplingProfiler.BinaryHprofReader;
-import dalvik.system.SamplingProfiler.BinaryHprofWriter;
-import dalvik.system.SamplingProfiler.HprofData.Sample;
-import dalvik.system.SamplingProfiler.HprofData.StackTrace;
-import dalvik.system.SamplingProfiler.HprofData.ThreadEvent;
-import dalvik.system.SamplingProfiler.HprofData;
-import dalvik.system.SamplingProfiler.HprofWriter;
-import dalvik.system.SamplingProfiler.ThreadSet;
+package dalvik.system.profiler;
+
+import dalvik.system.profiler.AsciiHprofWriter;
+import dalvik.system.profiler.BinaryHprofReader;
+import dalvik.system.profiler.BinaryHprofWriter;
+import dalvik.system.profiler.HprofData.Sample;
+import dalvik.system.profiler.HprofData.StackTrace;
+import dalvik.system.profiler.HprofData.ThreadEvent;
+import dalvik.system.profiler.HprofData;
+import dalvik.system.profiler.HprofWriter;
+import dalvik.system.profiler.SamplingProfiler.ThreadSet;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
@@ -221,8 +221,8 @@ public class SamplingProfilerTest extends TestCase {
     private void assertHprofData(HprofData hprofData, boolean strict) throws Exception {
         List<ThreadEvent> threadHistory = hprofData.getThreadHistory();
         assertNotNull(threadHistory);
-        Set<Integer> threadsSeen = new HashSet();
-        Set<Integer> threadsActive = new HashSet();
+        Set<Integer> threadsSeen = new HashSet<Integer>();
+        Set<Integer> threadsActive = new HashSet<Integer>();
         for (ThreadEvent event : threadHistory) {
             assertNotNull(event);
             assertNotNull(event.type);