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Commit dbe2bbbd authored by Narayan Kamath's avatar Narayan Kamath
Browse files

ActivityManagerService: Add an overall stack dumping timeout. 

An ANR can result in stack dumps of a generally unbounded number
of processes. Dumping occurs on a thread that's patrolled by the
watchdog, so we should make sure that all dumps trigger within a
specified timeout.

Test: Manual; by setting the timeout to 1s.
Bug: 37177331

Change-Id: I626272dfbcc9f8b57c1ef1321fac43cdb937a885
parent 9dee9753

services/core/java/com/android/server/am/ActivityManagerService.java

+69 −18
Original line number Diff line number Diff line
@@ -5427,7 +5427,7 @@ public class ActivityManagerService extends IActivityManager.Stub 
    public static class DumpStackFileObserver extends FileObserver {

        // Keep in sync with frameworks/native/cmds/dumpstate/utils.cpp

        private static final int TRACE_DUMP_TIMEOUT_MS = 10000; // 10 seconds

        static final int TRACE_DUMP_TIMEOUT_SECONDS = TRACE_DUMP_TIMEOUT_MS / 1000;

        static final int NATIVE_DUMP_TIMEOUT_MS = 2000; // 2 seconds;















        private final String mTracesPath;















        private boolean mClosed;









@@ -5443,21 +5443,41 @@ public class ActivityManagerService extends IActivityManager.Stub













            notify();















        }



























        public void dumpWithTimeout(int pid) {













        public long dumpWithTimeout(int pid, long timeout) {















            sendSignal(pid, SIGNAL_QUIT);













            final long start = SystemClock.elapsedRealtime();

























            final long waitTime = Math.min(timeout, TRACE_DUMP_TIMEOUT_MS);















            synchronized (this) {















                try {













                    wait(TRACE_DUMP_TIMEOUT_MS); // Wait for traces file to be closed.













                    wait(waitTime); // Wait for traces file to be closed.















                } catch (InterruptedException e) {















                    Slog.wtf(TAG, e);















                }















            }

























            // This avoids a corner case of passing a negative time to the native













            // trace in case we've already hit the overall timeout.













            final long timeWaited = SystemClock.elapsedRealtime() - start;













            if (timeWaited >= timeout) {













                return timeWaited;













            }



























            if (!mClosed) {















                Slog.w(TAG, "Didn't see close of " + mTracesPath + " for pid " + pid +















                       ". Attempting native stack collection.");













                Debug.dumpNativeBacktraceToFileTimeout(pid, mTracesPath, TRACE_DUMP_TIMEOUT_SECONDS);

























                final long nativeDumpTimeoutMs = Math.min(













                        NATIVE_DUMP_TIMEOUT_MS, timeout - timeWaited);

























                Debug.dumpNativeBacktraceToFileTimeout(pid, mTracesPath,













                        (int) (nativeDumpTimeoutMs / 1000));















            }

























            final long end = SystemClock.elapsedRealtime();















            mClosed = false;

























            return (end - start);















        }















    }























@@ -5467,6 +5487,9 @@ public class ActivityManagerService extends IActivityManager.Stub













        // Use a FileObserver to detect when traces finish writing.















        // The order of traces is considered important to maintain for legibility.















        DumpStackFileObserver observer = new DumpStackFileObserver(tracesPath);

























        // We must complete all stack dumps within 20 seconds.













        long remainingTime = 20 * 1000;















        try {















            observer.startWatching();























@@ -5476,10 +5499,18 @@ public class ActivityManagerService extends IActivityManager.Stub













                for (int i = 0; i < num; i++) {















                    if (DEBUG_ANR) Slog.d(TAG, "Collecting stacks for pid "















                            + firstPids.get(i));













                    final long sime = SystemClock.elapsedRealtime();













                    observer.dumpWithTimeout(firstPids.get(i));













                    if (DEBUG_ANR) Slog.d(TAG, "Done with pid " + firstPids.get(i)













                            + " in " + (SystemClock.elapsedRealtime()-sime) + "ms");













                    final long timeTaken = observer.dumpWithTimeout(firstPids.get(i), remainingTime);

























                    remainingTime -= timeTaken;













                    if (remainingTime <= 0) {













                        Slog.e(TAG, "Aborting stack trace dump (current firstPid=" + firstPids.get(i) +













                            "); deadline exceeded.");













                        return;













                    }

























                    if (DEBUG_ANR) {













                        Slog.d(TAG, "Done with pid " + firstPids.get(i) + " in " + timeTaken + "ms");













                    }















                }















            }























@@ -5487,12 +5518,24 @@ public class ActivityManagerService extends IActivityManager.Stub













            if (nativePids != null) {















                for (int pid : nativePids) {















                    if (DEBUG_ANR) Slog.d(TAG, "Collecting stacks for native pid " + pid);













                    final long sime = SystemClock.elapsedRealtime();













                    final long nativeDumpTimeoutMs = Math.min(













                            DumpStackFileObserver.NATIVE_DUMP_TIMEOUT_MS, remainingTime);



























                    final long start = SystemClock.elapsedRealtime();















                    Debug.dumpNativeBacktraceToFileTimeout(













                            pid, tracesPath, DumpStackFileObserver.TRACE_DUMP_TIMEOUT_SECONDS);













                    if (DEBUG_ANR) Slog.d(TAG, "Done with native pid " + pid













                            + " in " + (SystemClock.elapsedRealtime()-sime) + "ms");













                            pid, tracesPath, (int) (nativeDumpTimeoutMs / 1000));













                    final long timeTaken = SystemClock.elapsedRealtime() - start;

























                    remainingTime -= timeTaken;













                    if (remainingTime <= 0) {













                        Slog.e(TAG, "Aborting stack trace dump (current native pid=" + pid +













                            "); deadline exceeded.");













                        return;













                    }

























                    if (DEBUG_ANR) {













                        Slog.d(TAG, "Done with native pid " + pid + " in " + timeTaken + "ms");













                    }















                }















            }























@@ -5516,12 +5559,20 @@ public class ActivityManagerService extends IActivityManager.Stub













                    ProcessCpuTracker.Stats stats = processCpuTracker.getWorkingStats(i);















                    if (lastPids.indexOfKey(stats.pid) >= 0) {















                        numProcs++;













                        if (DEBUG_ANR) Slog.d(TAG, "Collecting stacks for extra pid "













                                + stats.pid);













                        final long stime = SystemClock.elapsedRealtime();













                        observer.dumpWithTimeout(stats.pid);













                        if (DEBUG_ANR) Slog.d(TAG, "Done with extra pid " + stats.pid













                                + " in " + (SystemClock.elapsedRealtime()-stime) + "ms");

























                        if (DEBUG_ANR) Slog.d(TAG, "Collecting stacks for extra pid " + stats.pid);

























                        final long timeTaken = observer.dumpWithTimeout(stats.pid, remainingTime);













                        remainingTime -= timeTaken;













                        if (remainingTime <= 0) {













                            Slog.e(TAG, "Aborting stack trace dump (current extra pid=" + stats.pid +













                                "); deadline exceeded.");













                            return;













                        }

























                        if (DEBUG_ANR) {













                            Slog.d(TAG, "Done with extra pid " + stats.pid + " in " + timeTaken + "ms");













                        }















                    } else if (DEBUG_ANR) {















                        Slog.d(TAG, "Skipping next CPU consuming process, not a java proc: "















                                + stats.pid);