企业网站建设立项书,wordpress如何精简导航代码,wordpress免费中文主题,营口门户网站建设一、前言 在Service组件StartService()方式启动流程分析文章中#xff0c;针对Context#startService()启动Service流程分析了源码#xff0c;其实关于Service启动还有一个比较重要的点是Service启动的ANR#xff0c;因为因为线上出现了上百例的executing service 针对Context#startService()启动Service流程分析了源码其实关于Service启动还有一个比较重要的点是Service启动的ANR因为因为线上出现了上百例的executing service service.shortName的异常。
二、Service-ANR原理
2.1 Service启动ANR原理简述 Service的ANR触发原理是在启动Service前使用Handler发送一个延时的Message埋炸弹过程然后在Service启动完成后remove掉这个Message拆炸弹过程。如果在指定的延迟时间内没有remove掉这个Message那么就会触发ANR没有在炸弹爆炸前拆掉就会爆炸弹出AppNotResponding的弹窗。 其实这个机制跟Windows/MacOS的应用程序无响应是类似的交互设计。
2.2 前台Service VS 后台Service的区别
2.2.1 前台Service 前台Service是一种在通知栏中显示持续通知的服务它通常用于执行用户明确知晓的任务比如音乐播放器、定位服务等。前台Service在系统内部被视为用户正在主动使用的组件因此它具有更高的优先级和较低的系统资源限制。在使用前台Service时必须在通知栏中显示一个通知以告知用户有一个正在运行的Service并且通常还应该提供一些与该Service相关的有用信息。
2.2.3 后台Service 后台Service是一种不会在通知栏中显示通知的服务。它用于执行一些不需要用户直接交互或注意的任务例如数据同步、网络请求等。后台Service具有较低的系统优先级系统可能会在资源紧张的情况下终止这些服务以释放资源。
2.3 Service启动ANR源码执行过程 ps: 还是基于Android SDK28源码分析 基于文章Service组件StartService()方式启动流程分析的总结我们已经很清楚通过startService的方式启动Service的源码过程。因此本文直接从com.android.server.am.ActiveServices#bringUpServiceLocked方法的源码开始分析如有不清楚前置的启动流程的同学可以参考我之前的文章然后打开AS对照看下这部分的代码。
2.3.1 ActiveServices#bringUpServiceLocked private String bringUpServiceLocked(ServiceRecord r, int intentFlags, boolean execInFg,boolean whileRestarting, boolean permissionsReviewRequired)throws TransactionTooLargeException {if (r.app ! null r.app.thread ! null) {sendServiceArgsLocked(r, execInFg, false);return null;}realStartServiceLocked(r, app, execInFg);}2.3.2 ActiveServices#realStartServiceLocked
private final void realStartServiceLocked(ServiceRecord r,ProcessRecord app, boolean execInFg) throws RemoteException {// ...// 会转调到scheduleServiceTimeoutLocked(r.app)方法进行埋炸弹操作bumpServiceExecutingLocked(r, execInFg, create);try {app.thread.scheduleCreateService(r, r.serviceInfo,mAm.compatibilityInfoForPackageLocked(r.serviceInfo.applicationInfo),app.repProcState);} catch (DeadObjectException e) {mAm.appDiedLocked(app);throw e;} finally {// serviceDoneExecutingLocked方法内会拆除炸弹serviceDoneExecutingLocked(r, inDestroying, inDestroying);// ...}
}2.3.3 埋炸弹过程ActiveServices#bumpServiceExecutingLocked
private final void bumpServiceExecutingLocked(ServiceRecord r, boolean fg, String why) {// ...scheduleServiceTimeoutLocked(r.app);// ...
}com.android.server.am.ActiveServices#scheduleServiceTimeoutLocked
void scheduleServiceTimeoutLocked(ProcessRecord proc) {if (proc.executingServices.size() 0 || proc.thread null) {return;}Message msg mAm.mHandler.obtainMessage(ActivityManagerService.SERVICE_TIMEOUT_MSG);msg.obj proc;mAm.mHandler.sendMessageDelayed(msg,proc.execServicesFg ? SERVICE_TIMEOUT : SERVICE_BACKGROUND_TIMEOUT);
}这里需要知道炸弹的爆炸时间在ActiveServices中定义了三个
// 前台Service的超时时间是20s
static final int SERVICE_TIMEOUT 20*1000;
// 后台Service的超时时间是200s是前台超时时间的10倍
static final int SERVICE_BACKGROUND_TIMEOUT SERVICE_TIMEOUT * 10;
// How long the startForegroundService() grace period is to get around to
// calling startForeground() before we ANR stop it.
static final int SERVICE_START_FOREGROUND_TIMEOUT 10*1000;2.3.4 拆炸弹过程ActiveServices#serviceDoneExecutingLocked
private void serviceDoneExecutingLocked(ServiceRecord r, boolean inDestroying,boolean finishing) {// ...mAm.mHandler.removeMessages(ActivityManagerService.SERVICE_TIMEOUT_MSG, r.app); // ...
}2.3.5 炸弹爆炸出发ANR弹窗过程 如上文分析的ANR弹窗其实就是一个sendMessageDelayed()方式发送的一个Message想要了解ANR炸弹这么爆炸的其实检索这个what值为ActivityManagerService.SERVICE_TIMEOUT_MSG的消息处理过程即可。 这个消息的Handler对应的handleMessage方法实现代码在AMS.java中。
com.android.server.am.ActivityManagerService.MainHandler#handleMessage
final class MainHandler extends Handler {public MainHandler(Looper looper) {super(looper, null, true);}Overridepublic void handleMessage(Message msg) {switch (msg.what) {// ...case SERVICE_TIMEOUT_MSG: {mServices.serviceTimeout((ProcessRecord)msg.obj);} break;case SERVICE_FOREGROUND_TIMEOUT_MSG: {mServices.serviceForegroundTimeout((ServiceRecord)msg.obj);} break;case SERVICE_FOREGROUND_CRASH_MSG: {mServices.serviceForegroundCrash((ProcessRecord) msg.obj, msg.getData().getCharSequence(SERVICE_RECORD_KEY));} break;// ...}}com.android.server.am.ActiveServices#serviceTimeout
void serviceTimeout(ProcessRecord proc) {String anrMessage null;synchronized(mAm) {if (proc.executingServices.size() 0 || proc.thread null) {return;}final long now SystemClock.uptimeMillis();final long maxTime now -(proc.execServicesFg ? SERVICE_TIMEOUT : SERVICE_BACKGROUND_TIMEOUT);ServiceRecord timeout null;long nextTime 0;for (int iproc.executingServices.size()-1; i0; i--) {ServiceRecord sr proc.executingServices.valueAt(i);if (sr.executingStart maxTime) {timeout sr;break;}if (sr.executingStart nextTime) {nextTime sr.executingStart;}}if (timeout ! null mAm.mLruProcesses.contains(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);// 这一句对于我们分析问题比较关键如果有Service的ANR// 就会在log中有这样的前缀打印executing service Service.shortNameanrMessage executing service timeout.shortName;} else {Message msg mAm.mHandler.obtainMessage(ActivityManagerService.SERVICE_TIMEOUT_MSG);msg.obj proc;mAm.mHandler.sendMessageAtTime(msg, proc.execServicesFg? (nextTimeSERVICE_TIMEOUT) : (nextTime SERVICE_BACKGROUND_TIMEOUT));}}// 真正触发ANR弹窗的位置if (anrMessage ! null) {mAm.mAppErrors.appNotResponding(proc, null, null, false, anrMessage);}
}这里记住anrMessage的格式是executing service Service.shortName代表的是Service的启动超时。
com.android.server.am.AppErrors#appNotResponding
final void appNotResponding(ProcessRecord app, ActivityRecord activity, ActivityRecord parent, boolean aboveSystem, final String annotation) {if (mService.mController ! null) {try {// 0 continue, -1 kill process immediately// 关键mService.mController的实现类是// com.android.server.am.ActivityManagerShellCommand.MyActivityControllerint res mService.mController.appEarlyNotResponding(app.processName, app.pid, annotation);if (res 0 app.pid ! MY_PID) {app.kill(anr, true);}} catch (RemoteException e) {mService.mController null;Watchdog.getInstance().setActivityController(null);}long anrTime SystemClock.uptimeMillis();if (ActivityManagerService.MONITOR_CPU_USAGE) {mService.updateCpuStatsNow();}// Unless configured otherwise, swallow ANRs in background processes // kill the process.// 读取开发者选项中的“显示后台ANR”开关boolean showBackground Settings.Secure.getInt(mContext.getContentResolver(),Settings.Secure.ANR_SHOW_BACKGROUND, 0) ! 0;boolean isSilentANR;// Dont dump other PIDs if its a background ANRisSilentANR !showBackground !isInterestingForBackgroundTraces(app);// Log the ANR to the main log.StringBuilder info new StringBuilder();info.setLength(0);// 这里可以看出写入到日志文件中的格式是ANR in processName// 比如我们应用包名是com.techmix.myapp// 那可在搜索时直接输入ANR in com.techminx.myapp搜索可更高效定位到ANR的trace位置info.append(ANR in ).append(app.processName);if (activity ! null activity.shortComponentName ! null) {info.append( ().append(activity.shortComponentName).append());}info.append(\n);info.append(PID: ).append(app.pid).append(\n);if (annotation ! null) {// 这里的reason还是serviceTimeout中定义的Service启动的anrMessage字符串// executing service Service.shortName没有多余的更明细的分类了具体是哪一步ANR了。info.append(Reason: ).append(annotation).append(\n);}if (parent ! null parent ! activity) {info.append(Parent: ).append(parent.shortComponentName).append(\n);}ProcessCpuTracker processCpuTracker new ProcessCpuTracker(true);// For background ANRs, dont pass the ProcessCpuTracker to// avoid spending 1/2 second collecting stats to rank lastPids.File tracesFile ActivityManagerService.dumpStackTraces(true, firstPids,(isSilentANR) ? null : processCpuTracker, (isSilentANR) ? null : lastPids, nativePids);// 写入cpu占用信息到anr log中String cpuInfo null;if (ActivityManagerService.MONITOR_CPU_USAGE) {mService.updateCpuStatsNow();synchronized (mService.mProcessCpuTracker) {cpuInfo mService.mProcessCpuTracker.printCurrentState(anrTime);}info.append(processCpuTracker.printCurrentLoad());info.append(cpuInfo);}info.append(processCpuTracker.printCurrentState(anrTime));// ANR log写入到dropbox文件夹中annotation变量就是// com.android.server.am.ActiveServices#serviceTimeout中传入的anrMessage变量mService.addErrorToDropBox(anr, app, app.processName, activity, parent, annotation,cpuInfo, tracesFile, null);synchronized (mService) {// 静默ANR的定义if (isSilentANR) {app.kill(bg anr, true);return;}// 通过Handler发送ANR弹窗的dialog这里直接跟进// ActivityManagerService.SHOW_NOT_RESPONDING_UI_MSG这个消息的handleMessage处理逻辑即可Message msg Message.obtain();msg.what ActivityManagerService.SHOW_NOT_RESPONDING_UI_MSG;msg.obj new AppNotRespondingDialog.Data(app, activity, aboveSystem);// 注意这里的mService是AMSmService.mUiHandler.sendMessage(msg);}
}静默ANR的定义弹出ANR弹窗的逻辑代码com.android.server.am.ActivityManagerService.UiHandler#handleMessage
case SHOW_NOT_RESPONDING_UI_MSG: {// 还是转调到AppErrors中的方法去实现了所以这里只是用AMS中的UiHandler切换了一下线程而已// 最开始的startService方法从应用主线程// ContextImpl#startService-AMS#startService()后者其实是执行在binder线程池的线程里// 面的是子线程。所以这里通过消息的方式切到主线程mAppErrors.handleShowAnrUi(msg);ensureBootCompleted();} break;com.android.server.am.AppErrors#handleShowAnrUi // 跟ANR相关的变量直接存储在了ProcessRecord.java类中每个进程单独维护一个boolean notResponding; // does the app have a not responding dialog?Dialog anrDialog; // dialog being displayed due to app not resp.void handleShowAnrUi(Message msg) {Dialog dialogToShow null;synchronized (mService) {AppNotRespondingDialog.Data data (AppNotRespondingDialog.Data) msg.obj;final ProcessRecord proc data.proc;if (proc null) {Slog.e(TAG, handleShowAnrUi: proc is null);return;}if (proc.anrDialog ! null) {Slog.e(TAG, App already has anr dialog: proc);MetricsLogger.action(mContext, MetricsProto.MetricsEvent.ACTION_APP_ANR,AppNotRespondingDialog.ALREADY_SHOWING);return;}// 这个ANR的广播应用进程如果注册了能接收到吗Intent intent new Intent(android.intent.action.ANR);if (!mService.mProcessesReady) {intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY| Intent.FLAG_RECEIVER_FOREGROUND);}mService.broadcastIntentLocked(null, null, intent,null, null, 0, null, null, null, AppOpsManager.OP_NONE,null, false, false, MY_PID, Process.SYSTEM_UID, 0 /* TODO: Verify */);boolean showBackground Settings.Secure.getInt(mContext.getContentResolver(),Settings.Secure.ANR_SHOW_BACKGROUND, 0) ! 0;if (mService.canShowErrorDialogs() || showBackground) {dialogToShow new AppNotRespondingDialog(mService, mContext, data);proc.anrDialog dialogToShow;} else {MetricsLogger.action(mContext, MetricsProto.MetricsEvent.ACTION_APP_ANR,AppNotRespondingDialog.CANT_SHOW);// 如果ANR弹窗是关闭状态下直接kill当前应用进程了// 跟ANR弹窗中点关闭应用一样多是调用AMS#killAppAtUsersRequest方法// 关闭当前进程mService.killAppAtUsersRequest(proc, null);}}// If weve created a crash dialog, show it without the lock heldif (dialogToShow ! null) {dialogToShow.show();}}com.android.server.am.AppErrors#killAppAtUserRequestLocked void killAppAtUserRequestLocked(ProcessRecord app, Dialog fromDialog) {app.crashing false;app.crashingReport null;app.notResponding false;app.notRespondingReport null;if (app.anrDialog fromDialog) {app.anrDialog null;}if (app.waitDialog fromDialog) {app.waitDialog null;}// 这里的MY_PID是定义在AMS中的static final int MY_PID myPid();// 所以这里只要是有效的应用pid都是能进入if逻辑分支中的if (app.pid 0 app.pid ! MY_PID) {handleAppCrashLocked(app, user-terminated /*reason*/,null /*shortMsg*/, null /*longMsg*/, null /*stackTrace*/, null /*data*/);app.kill(user request after error, true);}}app.kill()调用的是ProcessRecord#kill()最终转调到AMS#killProcessGroup()方法了。这里AMS方式kill掉进程的在Android的logcat中其实都能搜索到Activity Manager killing的字样的。
