Service生命周期時序圖
Service.onCreate()←ApplicationThreadProxy.scheduleCreateService()←realStartServiceLocked()
調(diào)用scheduleCreateService()前會調(diào)用bumpServiceExecutingLocked()

Service.onBind()/onRebind()←ApplicationThreadProxy.scheduleBindService()←
requestServiceBindingLocked()
調(diào)用 scheduleBindService()前會調(diào)用bumpServiceExecutingLocked()

Service.onStartCommand←ApplicationThreadProxy.scheduleServiceArgs()←sendServiceArgsLocked()
調(diào)用 scheduleServiceArgs()前會調(diào)用bumpServiceExecutingLocked()

Service.onUnbind()←ApplicationThreadProxy.scheduleUnbindService()←removeConnectionLocked()
調(diào)用 scheduleUnbindService()前會調(diào)用bumpServiceExecutingLocked()

Service.onDestroy()←ApplicationThreadProxy.scheduleStopService()←bringDownServiceLocked()
調(diào)用 scheduleStopService()前會調(diào)用bumpServiceExecutingLocked()

ActiveServices.bumpServiceExecutingLocked()→
ActiveServices.scheduleServiceTimeoutLocked()→...→
ActiveServices.serviceTimeout()→...→
ActivityManagerSerivce.appNotResponding()→...→
Dialog.show()

ActiveServices.java

static final int SERVICE_TIMEOUT = 20*1000;

static final int SERVICE_BACKGROUND_TIMEOUT = SERVICE_TIMEOUT * 10;

final ActivityManagerService mAm;

void scheduleServiceTimeoutLocked(ProcessRecord proc) {
    if (proc.executingServices.size() == 0 || proc.thread == null) {
        return;
    }
    long now = SystemClock.uptimeMillis();
    Message msg = mAm.mHandler.obtainMessage(
            ActivityManagerService.SERVICE_TIMEOUT_MSG);
    msg.obj = proc;
    mAm.mHandler.sendMessageAtTime(msg,
            proc.execServicesFg ? (now+SERVICE_TIMEOUT) : (now+ SERVICE_BACKGROUND_TIMEOUT));
}

void serviceTimeout(ProcessRecord proc) {
    String anrMessage = null;
    ...
    if (anrMessage != null) {
        mAm.appNotResponding(proc, null, null, false, anrMessage);
    }
}

ActivityManagerService.java

final MainHandler mHandler;

final class MainHandler extends Handler {
    public MainHandler(Looper looper) {
        super(looper, null, true);
    }

    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
        ...
        case SERVICE_TIMEOUT_MSG: {
            ...
            mServices.serviceTimeout((ProcessRecord)msg.obj);
        } break;
    }
}

final void appNotResponding(ProcessRecord app, ActivityRecord activity,
        ActivityRecord parent, boolean aboveSystem, final String annotation) {
    ArrayList<Integer> firstPids = new ArrayList<Integer>(5);
    SparseArray<Boolean> lastPids = new SparseArray<Boolean>(20);
    ...
    synchronized (this) {
        // PowerManager.reboot() can block for a long time, so ignore ANRs while shutting down.
        if (mShuttingDown) {
            Slog.i(TAG, "During shutdown skipping ANR: " + app + " " + annotation);
            return;
        } else if (app.notResponding) {
            //已經(jīng)彈出ANR，再次ANR直接return
            Slog.i(TAG, "Skipping duplicate ANR: " + app + " " + annotation);
            return;
        } else if (app.crashing) {
            Slog.i(TAG, "Crashing app skipping ANR: " + app + " " + annotation);
            return;
        }

        // In case we come through here for the same app before completing
        // this one, mark as anring now so we will bail out.
         //標記ANR，避免多次執(zhí)行
        app.notResponding = true;

        // Log the ANR to the event log.
        EventLog.writeEvent(EventLogTags.AM_ANR, app.userId, app.pid,
                app.processName, app.info.flags, annotation);

        // Dump thread traces as quickly as we can, starting with "interesting" processes.
        firstPids.add(app.pid);

        int parentPid = app.pid;
        if (parent != null && parent.app != null && parent.app.pid > 0) parentPid = parent.app.pid;
        if (parentPid != app.pid) firstPids.add(parentPid);

        if (MY_PID != app.pid && MY_PID != parentPid) firstPids.add(MY_PID);

        for (int i = mLruProcesses.size() - 1; i >= 0; i--) {
            ProcessRecord r = mLruProcesses.get(i);
            if (r != null && r.thread != null) {
                int pid = r.pid;
                if (pid > 0 && pid != app.pid && pid != parentPid && pid != MY_PID) {
                    if (r.persistent) {
                        firstPids.add(pid);
                    } else {
                        lastPids.put(pid, Boolean.TRUE);
                    }
                }
            }
        }
    }

    // Log the ANR to the main log.
    StringBuilder info = new StringBuilder();
    info.setLength(0);
    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) {
        info.append("Reason: ").append(annotation).append("\\n");
    }
    if (parent != null && parent != activity) {
        info.append("Parent: ").append(parent.shortComponentName).append("\\n");
    }

    final ProcessCpuTracker processCpuTracker = new ProcessCpuTracker(true);

    File tracesFile = dumpStackTraces(true, firstPids, processCpuTracker, lastPids,
            NATIVE_STACKS_OF_INTEREST);

    String cpuInfo = null;
    if (MONITOR_CPU_USAGE) {
        updateCpuStatsNow();
        synchronized (mProcessCpuTracker) {
            cpuInfo = mProcessCpuTracker.printCurrentState(anrTime);
        }
        info.append(processCpuTracker.printCurrentLoad());
        info.append(cpuInfo);
    }

    info.append(processCpuTracker.printCurrentState(anrTime));

    Slog.e(TAG, info.toString());
    if (tracesFile == null) {
        // There is no trace file, so dump (only) the alleged culprit's threads to the log
        Process.sendSignal(app.pid, Process.SIGNAL_QUIT);
    }

    addErrorToDropBox("anr", app, app.processName, activity, parent, annotation,
            cpuInfo, tracesFile, null);
    ...
    // Unless configured otherwise, swallow ANRs in background processes & kill the process.
    boolean showBackground = Settings.Secure.getInt(mContext.getContentResolver(),
            Settings.Secure.ANR_SHOW_BACKGROUND, 0) != 0;

    synchronized (this) {
        mBatteryStatsService.noteProcessAnr(app.processName, app.uid);

        if (!showBackground && !app.isInterestingToUserLocked() && app.pid != MY_PID) {
            app.kill("bg anr", true);
            return;
        }

        // Set the app's notResponding state, and look up the errorReportReceiver
        makeAppNotRespondingLocked(app,
                activity != null ? activity.shortComponentName : null,
                annotation != null ? "ANR " + annotation : "ANR",
                info.toString());

        // Bring up the infamous App Not Responding dialog
        Message msg = Message.obtain();
        HashMap<String, Object> map = new HashMap<String, Object>();
        msg.what = SHOW_NOT_RESPONDING_MSG;
        msg.obj = map;
        msg.arg1 = aboveSystem ? 1 : 0;
        map.put("app", app);
        if (activity != null) {
            map.put("activity", activity);
        }

        mUiHandler.sendMessage(msg);
    }
}

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_MSG: {
                synchronized (ActivityManagerService.this) {
                    HashMap<String, Object> data = (HashMap<String, Object>) msg.obj;
                    ProcessRecord proc = (ProcessRecord)data.get("app");
                    if (proc != null && proc.anrDialog != null) {
                        Slog.e(TAG, "App already has anr dialog: " + proc);
                        return;
                    }

                    Intent intent = new Intent("android.intent.action.ANR");
                    if (!mProcessesReady) {
                       intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY| Intent.FLAG_RECEIVER_FOREGROUND);
                    }
                    broadcastIntentLocked(null, null, intent,
                        null, null, 0, null, null, null, AppOpsManager.OP_NONE,
                        null, false, false, MY_PID, Process.SYSTEM_UID, 0 /* TODO: Verify */);

                    if (mShowDialogs) {
                        Dialog d = new AppNotRespondingDialog(ActivityManagerService.this,
                            mContext, proc, (ActivityRecord)data.get("activity"),
                            msg.arg1 != 0);
                        d.show();
                        proc.anrDialog = d;
                    } else {
                        // Just kill the app if there is no dialog to be shown.
                        killAppAtUsersRequest(proc, null);
                    }
                }

                ensureBootCompleted();
            } break;
        }
    }
}

Service在執(zhí)行完生命周期方法后都會通知ActivityManagerService執(zhí)行serviceDoneExecuting()（這一步我并沒有在時序圖里畫出來，實在太多了）
serviceDoneExecuting()內(nèi)部會移除超時msg，所以如果超過20s（后臺服務(wù)200s，默認當然是后臺服務(wù)）還沒收到這個通知，那么超時msg就進入handleMessage

ActivityManagerService.serviceDoneExecuting()→
ActiveServices.serviceDoneExecutingLocked()

private void serviceDoneExecutingLocked(ServiceRecord r, boolean inDestroying,
        boolean finishing) {
    ...
    if (r.executeNesting <= 0) {
        if (r.app != null) {
            if (DEBUG_SERVICE) Slog.v(TAG_SERVICE,
                    "Nesting at 0 of " + r.shortName);
            r.app.execServicesFg = false;
            r.app.executingServices.remove(r);
            if (r.app.executingServices.size() == 0) {//app沒有正在執(zhí)行的service
                mAm.mHandler.removeMessages(ActivityManagerService.SERVICE_TIMEOUT_MSG, r.app);
            }
            ...
}