关于anr的知识复习

一知半解

从源码来看都哪种情况下会造成anr

• ActivitiManagerService
  ActivityManagerService是系统核心服务，统一管理着四大组件。关于四大组件的管理过程，一直是一知半解，应该写篇文章来好好复习总结一下，这里就先总结一下anr的分发过程吧。

  static final int SHOW_NOT_RESPONDING_UI_MSG = 2;
  final class UiHandler extends Handler {
        public UiHandler() {
            super(com.android.server.UiThread.get().getLooper(), null, true);
        }

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case SHOW_NOT_RESPONDING_UI_MSG: {
                mAppErrors.handleShowAnrUi(msg);
                ensureBootCompleted();
            } break;
        }

从中可以看出anr超时是通过handler来发送后更新ui的，handleSowAnrUi会弹出一个超时的dialog。接下来可以看看这个SHOW_NOT_RESPONDING_UI_MSG都是从哪里发出来的，就能知道哪种情况下会造成anr了。

• ProcessRecord
  所有的anrMessage都是从这个方法中发送出去的

 void appNotResponding(String activityShortComponentName, ApplicationInfo aInfo,
            String parentShortComponentName, WindowProcessController parentProcess,
            boolean aboveSystem, String annotation) {
        synchronized (mService) {
            // mBatteryStatsService can be null if the AMS is constructed with injector only. This
            // will only happen in tests.
            // mUiHandler can be null if the AMS is constructed with injector only. This will only
            // happen in tests.
            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(this, aInfo, aboveSystem);

                mService.mUiHandler.sendMessage(msg);
            }
        }
    }

有以下几个调用的地方：

1. ActivityManagerService

 public void appNotRespondingViaProvider(IBinder connection) {
  }
contentProvider的超时

2. ActivityManagerService

 /**
     * Handle input dispatching timeouts.
     * @return whether input dispatching should be aborted or not.
     */
    boolean inputDispatchingTimedOut(ProcessRecord proc, String activityShortComponentName,
            ApplicationInfo aInfo, String parentShortComponentName,
            WindowProcessController parentProcess, boolean aboveSystem, String reason) {
     

        if (proc != null) {
            synchronized (this) {
                if (proc.isDebugging()) {//debug时不弹anr框
                    return false;
                }

                if (proc.getActiveInstrumentation() != null) {//子进程里面不弹anr弹
                    Bundle info = new Bundle();
                    info.putString("shortMsg", "keyDispatchingTimedOut");
                    info.putString("longMsg", annotation);
                    finishInstrumentationLocked(proc, Activity.RESULT_CANCELED, info);
                    return true;
                }
            }
            proc.appNotResponding(activityShortComponentName, aInfo,
                    parentShortComponentName, parentProcess, aboveSystem, annotation);
        }

        return true;
    }
输入的超时，两种情况下不弹anr框：debug时，子进程里面。

3. ActiveServices

void serviceTimeout(ProcessRecord proc) {
}
后台服务超时

4. ActiveServices

  void serviceForegroundTimeout(ServiceRecord r) {
}
前台服务超时