Hopefully fix issue #2662536: Why is launcher being killed?

It looks like there was a subtle bug where Process.setOomAdj() could
return false just because the given process doesn't exist, even though
it is documented to only return false if OOM killing is not supported
at all.  This would cause the activity manager to fall into its code
path of trying to clean up processes itself, which it does a much
poorer problem at.  I am thinking we may be seeing this problem more
now that the activity manager is killing background processes itself
when there are too many of them.

In addition, this change cleans up and reduces some of the logging
around killing processes.

Finally, try to improve process LRU management a bit by taking
into account process dependencies.  Any dependent processes are
pulled up in the LRU list with the processes that is actually
moving.  Also, we bring a process up if someone accesses its content
provider.

Change-Id: I34ea161f839679345578ffe681e8d9c5d26ab948

2 files changed, 64 insertions, 16 deletions

diff --git a/services/java/com/android/server/am/ActivityManagerService.java b/services/java/com/android/server/am/ActivityManagerService.java
index 706e15a..948d292 100644
--- a/services/java/com/android/server/am/ActivityManagerService.java
+++ b/services/java/com/android/server/am/ActivityManagerService.java
@@ -321,12 +321,12 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
     static final int MAX_HIDDEN_APPS = 15;
     
     // We put empty content processes after any hidden processes that have
-    // been idle for less than 30 seconds.
-    static final long CONTENT_APP_IDLE_OFFSET = 30*1000;
+    // been idle for less than 15 seconds.
+    static final long CONTENT_APP_IDLE_OFFSET = 15*1000;
     
     // We put empty content processes after any hidden processes that have
-    // been idle for less than 60 seconds.
-    static final long EMPTY_APP_IDLE_OFFSET = 60*1000;
+    // been idle for less than 120 seconds.
+    static final long EMPTY_APP_IDLE_OFFSET = 120*1000;
     
     static {
         // These values are set in system/rootdir/init.rc on startup.
@@ -880,6 +880,11 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
     int mAdjSeq = 0;
 
     /**
+     * Current sequence id for process LRU updating.
+     */
+    int mLruSeq = 0;
+    
+    /**
      * Set to true if the ANDROID_SIMPLE_PROCESS_MANAGEMENT envvar
      * is set, indicating the user wants processes started in such a way
      * that they can use ANDROID_PROCESS_WRAPPER and know what will be
@@ -1588,8 +1593,8 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
         }
     }
 
-    private final void updateLruProcessLocked(ProcessRecord app,
-            boolean oomAdj, boolean updateActivityTime) {
+    private final void updateLruProcessInternalLocked(ProcessRecord app,
+            boolean oomAdj, boolean updateActivityTime, int bestPos) {
         // put it on the LRU to keep track of when it should be exited.
         int lrui = mLruProcesses.indexOf(app);
         if (lrui >= 0) mLruProcesses.remove(lrui);
@@ -1597,6 +1602,8 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
         int i = mLruProcesses.size()-1;
         int skipTop = 0;
         
+        app.lruSeq = mLruSeq;
+        
         // compute the new weight for this process.
         if (updateActivityTime) {
             app.lastActivityTime = SystemClock.uptimeMillis();
@@ -1619,6 +1626,7 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
             // Also don't let it kick out the first few "real" hidden processes.
             skipTop = MIN_HIDDEN_APPS;
         }
+        
         while (i >= 0) {
             ProcessRecord p = mLruProcesses.get(i);
             // If this app shouldn't be in front of the first N background
@@ -1626,7 +1634,7 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
             if (skipTop > 0 && p.setAdj >= HIDDEN_APP_MIN_ADJ) {
                 skipTop--;
             }
-            if (p.lruWeight <= app.lruWeight){
+            if (p.lruWeight <= app.lruWeight || i < bestPos) {
                 mLruProcesses.add(i+1, app);
                 break;
             }
@@ -1636,12 +1644,39 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
             mLruProcesses.add(0, app);
         }
         
+        // If the app is currently using a content provider or service,
+        // bump those processes as well.
+        if (app.connections.size() > 0) {
+            for (ConnectionRecord cr : app.connections) {
+                if (cr.binding != null && cr.binding.service != null
+                        && cr.binding.service.app != null
+                        && cr.binding.service.app.lruSeq != mLruSeq) {
+                    updateLruProcessInternalLocked(cr.binding.service.app, oomAdj,
+                            updateActivityTime, i+1);
+                }
+            }
+        }
+        if (app.conProviders.size() > 0) {
+            for (ContentProviderRecord cpr : app.conProviders.keySet()) {
+                if (cpr.app != null && cpr.app.lruSeq != mLruSeq) {
+                    updateLruProcessInternalLocked(cpr.app, oomAdj,
+                            updateActivityTime, i+1);
+                }
+            }
+        }
+        
         //Slog.i(TAG, "Putting proc to front: " + app.processName);
         if (oomAdj) {
             updateOomAdjLocked();
         }
     }
 
+    private final void updateLruProcessLocked(ProcessRecord app,
+            boolean oomAdj, boolean updateActivityTime) {
+        mLruSeq++;
+        updateLruProcessInternalLocked(app, oomAdj, updateActivityTime, 0);
+    }
+    
     private final boolean updateLRUListLocked(HistoryRecord r) {
         final boolean hadit = mLRUActivities.remove(r);
         mLRUActivities.add(r);
@@ -4677,8 +4712,10 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
         // Clean up already done if the process has been re-started.
         if (app.pid == pid && app.thread != null &&
                 app.thread.asBinder() == thread.asBinder()) {
-            Slog.i(TAG, "Process " + app.processName + " (pid " + pid
-                    + ") has died.");
+            if (!app.killedBackground) {
+                Slog.i(TAG, "Process " + app.processName + " (pid " + pid
+                        + ") has died.");
+            }
             EventLog.writeEvent(EventLogTags.AM_PROC_DIED, app.pid, app.processName);
             if (localLOGV) Slog.v(
                 TAG, "Dying app: " + app + ", pid: " + pid
@@ -7826,6 +7863,13 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
                 }
 
                 if (cpr.app != null) {
+                    if (r.setAdj >= VISIBLE_APP_ADJ) {
+                        // If this is a visible app accessing the provider,
+                        // make sure to count it as being accessed and thus
+                        // back up on the LRU list.  This is good because
+                        // content providers are often expensive to start.
+                        updateLruProcessLocked(cpr.app, false, true);
+                    }
                     updateOomAdjLocked(cpr.app);
                 }
 
@@ -8492,12 +8536,13 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
                     continue;
                 }
                 int adj = proc.setAdj;
-                if (adj >= worstType) {
+                if (adj >= worstType && !proc.killedBackground) {
                     Slog.w(TAG, "Killing " + proc + " (adj " + adj + "): " + reason);
                     EventLog.writeEvent(EventLogTags.AM_KILL, proc.pid,
                             proc.processName, adj, reason);
                     killed = true;
-                    Process.killProcess(pids[i]);
+                    proc.killedBackground = true;
+                    Process.killProcessQuiet(pids[i]);
                 }
             }
         }
@@ -9829,6 +9874,7 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
                     + " mFactoryTest=" + mFactoryTest);
             pw.println("  mGoingToSleep=" + mGoingToSleep);
             pw.println("  mLaunchingActivity=" + mLaunchingActivity);
+            pw.println("  mAdjSeq=" + mAdjSeq + " mLruSeq=" + mLruSeq);
         }
         
         return true;
@@ -14292,13 +14338,12 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
                     if (!app.killedBackground) {
                         numHidden++;
                         if (numHidden > MAX_HIDDEN_APPS) {
-                            Slog.i(TAG, "Kill " + app.processName
-                                    + " (pid " + app.pid + "): hidden #" + numHidden
-                                    + " beyond limit " + MAX_HIDDEN_APPS);
+                            Slog.i(TAG, "No longer want " + app.processName
+                                    + " (pid " + app.pid + "): hidden #" + numHidden);
                             EventLog.writeEvent(EventLogTags.AM_KILL, app.pid,
                                     app.processName, app.setAdj, "too many background");
                             app.killedBackground = true;
-                            Process.killProcess(app.pid);
+                            Process.killProcessQuiet(app.pid);
                         }
                     }
                 }
diff --git a/services/java/com/android/server/am/ProcessRecord.java b/services/java/com/android/server/am/ProcessRecord.java
index 7620468..f49a182 100644
--- a/services/java/com/android/server/am/ProcessRecord.java
+++ b/services/java/com/android/server/am/ProcessRecord.java
@@ -66,7 +66,8 @@ class ProcessRecord implements Watchdog.PssRequestor {
     boolean bad;                // True if disabled in the bad process list
     boolean killedBackground;   // True when proc has been killed due to too many bg
     IBinder forcingToForeground;// Token that is forcing this process to be foreground
-    int adjSeq;                 // Sequence id for identifying repeated trav
+    int adjSeq;                 // Sequence id for identifying oom_adj assignment cycles
+    int lruSeq;                 // Sequence id for identifying LRU update cycles
     ComponentName instrumentationClass;// class installed to instrument app
     ApplicationInfo instrumentationInfo; // the application being instrumented
     String instrumentationProfileFile; // where to save profiling
@@ -175,6 +176,8 @@ class ProcessRecord implements Watchdog.PssRequestor {
         pw.print(prefix); pw.print("persistent="); pw.print(persistent);
                 pw.print(" removed="); pw.print(removed);
                 pw.print(" persistentActivities="); pw.println(persistentActivities);
+        pw.print(prefix); pw.print("adjSeq="); pw.print(adjSeq);
+                pw.print(" lruSeq="); pw.println(lruSeq);
         if (killedBackground) {
             pw.print(prefix); pw.print("killedBackground="); pw.println(killedBackground);
         }