Fix sluggish to launch an app

The new trace feature/code in 4.0.4, which will dump the app stack
trace every 500ms if an app can't be launched within 500ms, is
holding the global ActivityManagerService lock unnecessarily. It
slows down the app's startup.

Change-Id: I91fbb043912b4d1fcf3e80d8ac4e61cd20ad89d1
Solution: move the trace file write operations out of sync block.

2 files changed, 24 insertions, 8 deletions

diff --git a/services/java/com/android/server/am/ActivityManagerService.java b/services/java/com/android/server/am/ActivityManagerService.java
index 3bed489..a274891 100644
--- a/services/java/com/android/server/am/ActivityManagerService.java
+++ b/services/java/com/android/server/am/ActivityManagerService.java
@@ -3004,7 +3004,7 @@ public final class ActivityManagerService extends ActivityManagerNative
         }
     }
 
-    final void logAppTooSlow(ProcessRecord app, long startTime, String msg) {
+    final void logAppTooSlow(int pid, long startTime, String msg) {
         if (IS_USER_BUILD) {
             return;
         }
@@ -3037,7 +3037,7 @@ public final class ActivityManagerService extends ActivityManagerNative
                 sb.append(msg);
                 FileOutputStream fos = new FileOutputStream(tracesFile);
                 fos.write(sb.toString().getBytes());
-                if (app == null) {
+                if (pid <= 0) {
                     fos.write("\n*** No application process!".getBytes());
                 }
                 fos.close();
@@ -3047,9 +3047,9 @@ public final class ActivityManagerService extends ActivityManagerNative
                 return;
             }
 
-            if (app != null) {
+            if (pid > 0) {
                 ArrayList<Integer> firstPids = new ArrayList<Integer>();
-                firstPids.add(app.pid);
+                firstPids.add(pid);
                 dumpStackTraces(tracesPath, firstPids, null, null);
             }
 
diff --git a/services/java/com/android/server/am/ActivityStack.java b/services/java/com/android/server/am/ActivityStack.java
index 86d3a1a..d581d33 100644
--- a/services/java/com/android/server/am/ActivityStack.java
+++ b/services/java/com/android/server/am/ActivityStack.java
@@ -307,11 +307,18 @@ final class ActivityStack {
                     // We don't at this point know if the activity is fullscreen,
                     // so we need to be conservative and assume it isn't.
                     Slog.w(TAG, "Activity pause timeout for " + r);
+                    int pid = -1;
+                    long pauseTime = 0;
+                    String m = null;
                     synchronized (mService) {
                         if (r.app != null) {
-                            mService.logAppTooSlow(r.app, r.pauseTime,
-                                    "pausing " + r);
+                            pid = r.app.pid;
                         }
+                        pauseTime = r.pauseTime;
+                        m = "pausing " + r;
+                    }
+                    if (pid > 0) {
+                        mService.logAppTooSlow(pid, pauseTime, m);
                     }
 
                     activityPaused(r != null ? r.appToken : null, true);
@@ -332,12 +339,21 @@ final class ActivityStack {
                 } break;
                 case LAUNCH_TICK_MSG: {
                     ActivityRecord r = (ActivityRecord)msg.obj;
+                    int pid = -1;
+                    long launchTickTime = 0;
+                    String m = null;
                     synchronized (mService) {
                         if (r.continueLaunchTickingLocked()) {
-                            mService.logAppTooSlow(r.app, r.launchTickTime,
-                                    "launching " + r);
+                            if (r.app != null) {
+                                pid = r.app.pid;
+                            }
+                            launchTickTime = r.launchTickTime;
+                            m = "launching " + r;
                         }
                     }
+                    if (pid > 0) {
+                        mService.logAppTooSlow(pid, launchTickTime, m);
+                    }
                 } break;
                 case DESTROY_TIMEOUT_MSG: {
                     ActivityRecord r = (ActivityRecord)msg.obj;