JuneLeo's Blog
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Service ANR 流程分析

发表于 更新于 
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ANR in com.autonavi.minimap
PID: 28415
Reason: executing service com.autonavi.minimap/com.alipay.mobile.common.logging.process.LogServiceInPushProcess

此问题发生在Service中超时，抛出异常的时机是在系统进程

Service启动 会使用Handler发送一个延时的消息

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void scheduleServiceTimeoutLocked(ProcessRecord proc) {
        if (proc.mServices.numberOfExecutingServices() == 0 || proc.getThread() == null) {
            return;
        }
        Message msg = mAm.mHandler.obtainMessage(
                ActivityManagerService.SERVICE_TIMEOUT_MSG);
        msg.obj = proc;
        mAm.mHandler.sendMessageDelayed(msg, proc.mServices.shouldExecServicesFg()
                ? SERVICE_TIMEOUT : SERVICE_BACKGROUND_TIMEOUT);
}

如果在timeout时间范围内没有移除此消息，将会触发ANR异常

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case SERVICE_TIMEOUT_MSG: {
      mServices.serviceTimeout((ProcessRecord) msg.obj);
} break;
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void serviceTimeout(ProcessRecord proc) {
        String anrMessage = null;
        synchronized(mAm) {
            if (timeout != null && mAm.mProcessList.isInLruListLOSP(proc)) {
                Slog.w(TAG, "Timeout executing service: " + timeout);
                StringWriter sw = new StringWriter();
                PrintWriter pw = new FastPrintWriter(sw, false, 1024);
                pw.println(timeout);
                timeout.dump(pw, "    ");
                pw.close();
                mLastAnrDump = sw.toString();
                mAm.mHandler.removeCallbacks(mLastAnrDumpClearer);
                mAm.mHandler.postDelayed(mLastAnrDumpClearer, LAST_ANR_LIFETIME_DURATION_MSECS);
                anrMessage = "executing service " + timeout.shortInstanceName;
            } else {
                Message msg = mAm.mHandler.obtainMessage(
                        ActivityManagerService.SERVICE_TIMEOUT_MSG);
                msg.obj = proc;
                mAm.mHandler.sendMessageAtTime(msg, psr.shouldExecServicesFg()
                        ? (nextTime+SERVICE_TIMEOUT) : (nextTime + SERVICE_BACKGROUND_TIMEOUT));
            }
        }

        if (anrMessage != null) {
            mAm.mAnrHelper.appNotResponding(proc, anrMessage);
        }

最终会调用AnrRecord中的 appNotResponding

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private static class AnrRecord {
       

        AnrRecord(ProcessRecord anrProcess, String activityShortComponentName,
                ApplicationInfo aInfo, String parentShortComponentName,
                WindowProcessController parentProcess, boolean aboveSystem, String annotation) {
         
        }

        void appNotResponding(boolean onlyDumpSelf) {
            mApp.mErrorState.appNotResponding(mActivityShortComponentName, mAppInfo,
                    mParentShortComponentName, mParentProcess, mAboveSystem, mAnnotation,
                    onlyDumpSelf);
        }
    }

其中ProcessErrorStateRecord是一个很关键的类,这里dump出了开头的日志，并且将dump出了anr文件

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void appNotResponding(String activityShortComponentName, ApplicationInfo aInfo,
            String parentShortComponentName, WindowProcessController parentProcess,
            boolean aboveSystem, String annotation, boolean onlyDumpSelf) {

		...
    	// 1.控制台输出日志
        StringBuilder info = new StringBuilder();
        info.setLength(0);
        info.append("ANR in ").append(mApp.processName);
        if (activityShortComponentName != null) {
            info.append(" (").append(activityShortComponentName).append(")");
        }
        info.append("\n");
        info.append("PID: ").append(pid).append("\n");
        if (annotation != null) {
            info.append("Reason: ").append(annotation).append("\n");
        }
        if (parentShortComponentName != null
                && parentShortComponentName.equals(activityShortComponentName)) {
            info.append("Parent: ").append(parentShortComponentName).append("\n");
        }
        if (errorId != null) {
            info.append("ErrorId: ").append(errorId.toString()).append("\n");
        }
        info.append("Frozen: ").append(mApp.mOptRecord.isFrozen()).append("\n");
    
    
    	...
        // 2.写入/data/anr/anr_xxxx_xx 文件
        File tracesFile = ActivityManagerService.dumpStackTraces(firstPids,
                isSilentAnr ? null : processCpuTracker, isSilentAnr ? null : lastPids,
                nativePids, tracesFileException, offsets, annotation);
    
    	// 3.弹出anr dialog
        if (mService.mUiHandler != null) {
                // Bring up the infamous App Not Responding dialog
                Message msg = Message.obtain();
                msg.what = ActivityManagerService.SHOW_NOT_RESPONDING_UI_MSG;
                msg.obj = new AppNotRespondingDialog.Data(mApp, aInfo, aboveSystem);

                mService.mUiHandler.sendMessageDelayed(msg, anrDialogDelayMs);
       }
    	
    
}

AMS 中获取/data/anr/anr_xxxx_xx_xx 文件路径

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public static final String ANR_TRACE_DIR = "/data/anr";

/* package */ static File dumpStackTraces(ArrayList<Integer> firstPids,
            ProcessCpuTracker processCpuTracker, SparseArray<Boolean> lastPids,
            ArrayList<Integer> nativePids, StringWriter logExceptionCreatingFile,
            long[] firstPidOffsets, String subject) {
		....
        // anr文件
        final File tracesDir = new File(ANR_TRACE_DIR);
      	
        File tracesFile;
        try {
            tracesFile = createAnrDumpFile(tracesDir);
        } catch (IOException e) {
          
            return null;
        }
    	
        Pair<Long, Long> offsets = dumpStackTraces(
                tracesFile.getAbsolutePath(), firstPids, nativePids, extraPids);
        if (firstPidOffsets != null) {
            if (offsets == null) {
                firstPidOffsets[0] = firstPidOffsets[1] = -1;
            } else {
                firstPidOffsets[0] = offsets.first; // Start offset to the ANR trace file
                firstPidOffsets[1] = offsets.second; // End offset to the ANR trace file
            }
        }
        return tracesFile;
    }

    static final String ANR_FILE_PREFIX = "anr_";

    private static synchronized File createAnrDumpFile(File tracesDir) throws IOException {
        if (sAnrFileDateFormat == null) {
            sAnrFileDateFormat = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss-SSS");
        }

        final String formattedDate = sAnrFileDateFormat.format(new Date());
        final File anrFile = new File(tracesDir, ANR_FILE_PREFIX + formattedDate);

   
    }

Debug

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/**
     * Append the Java stack traces of a given native process to a specified file.
     *
     * @param pid pid to dump.
     * @param file path of file to append dump to.
     * @param timeoutSecs time to wait in seconds, or 0 to wait forever.
     * @hide
     */
    public static native boolean dumpJavaBacktraceToFileTimeout(int pid, String file,
                                                                int timeoutSecs);