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Commit 00348e66 authored by Jing Ji's avatar Jing Ji
Browse files

Dump stack trace without holding the global lock in Watchdog 

Since the dumping could last quite long.

Bug: 182937137
Test: adb shell am hang & check the log
Change-Id: I60c0b4aa5fab2f7e7ed6c9bea0365956b446967c
parent 7972c833

services/core/java/com/android/server/Watchdog.java

+28 −18
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ import java.io.IOException; 
import java.io.StringWriter;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashSet;

import java.util.List;

import java.util.concurrent.TimeUnit;
@@ -585,10 +586,12 @@ public class Watchdog { 
    private void run() {

        boolean waitedHalf = false;

        while (true) {

            final List<HandlerChecker> blockedCheckers;

            final String subject;

            final boolean allowRestart;

            List<HandlerChecker> blockedCheckers = Collections.emptyList();

            String subject = "";

            boolean allowRestart = true;

            int debuggerWasConnected = 0;

            boolean doWaitedHalfDump = false;

            final ArrayList<Integer> pids;

            synchronized (mLock) {

                long timeout = CHECK_INTERVAL;

                // Make sure we (re)spin the checkers that have become idle within
@@ -634,20 +637,28 @@ public class Watchdog { 
                } else if (waitState == WAITED_HALF) {

                    if (!waitedHalf) {

                        Slog.i(TAG, "WAITED_HALF");

                        // We've waited half the deadlock-detection interval.  Pull a stack

                        // trace and wait another half.

                        ArrayList<Integer> pids = new ArrayList<>(mInterestingJavaPids);

                        ActivityManagerService.dumpStackTraces(pids, null, null,

                                getInterestingNativePids(), null);

                        waitedHalf = true;

                    }

                        // We've waited half, but we'd need to do the stack trace dump w/o the lock.

                        pids = new ArrayList<>(mInterestingJavaPids);

                        doWaitedHalfDump = true;

                    } else {

                        continue;

                    }



                } else {

                    // something is overdue!

                    blockedCheckers = getBlockedCheckersLocked();

                    subject = describeCheckersLocked(blockedCheckers);

                    allowRestart = mAllowRestart;

                    pids = new ArrayList<>(mInterestingJavaPids);

                }

            } // END synchronized (mLock)



            if (doWaitedHalfDump) {

                // We've waited half the deadlock-detection interval.  Pull a stack

                // trace and wait another half.

                ActivityManagerService.dumpStackTraces(pids, null, null,

                        getInterestingNativePids(), null);

                continue;

            }



            // If we got here, that means that the system is most likely hung.
@@ -655,8 +666,6 @@ public class Watchdog { 
            // Then kill this process so that the system will restart.

            EventLog.writeEvent(EventLogTags.WATCHDOG, subject);



            ArrayList<Integer> pids = new ArrayList<>(mInterestingJavaPids);



            long anrTime = SystemClock.uptimeMillis();

            StringBuilder report = new StringBuilder();

            report.append(MemoryPressureUtil.currentPsiState());
@@ -681,6 +690,7 @@ public class Watchdog { 
            // Try to add the error to the dropbox, but assuming that the ActivityManager

            // itself may be deadlocked.  (which has happened, causing this statement to

            // deadlock and the watchdog as a whole to be ineffective)

            final String localSubject = subject;

            Thread dropboxThread = new Thread("watchdogWriteToDropbox") {

                    public void run() {

                        // If a watched thread hangs before init() is called, we don't have a
@@ -688,10 +698,10 @@ public class Watchdog { 
                        if (mActivity != null) {

                            mActivity.addErrorToDropBox(

                                    "watchdog", null, "system_server", null, null, null,

                                    subject, report.toString(), stack, null, null, null);

                                    localSubject, report.toString(), stack, null, null, null);

                        }

                        FrameworkStatsLog.write(FrameworkStatsLog.SYSTEM_SERVER_WATCHDOG_OCCURRED,

                                subject);

                                localSubject);

                    }

                };

            dropboxThread.start();