稳定性案例 --关机block

老化测试，在某次重启时卡在如下界面，在aplog里搜索shutdownthread关键字，看到流程在关闭ActivityManager时卡住了：

Line 302344: 05-02 05:03:17.286 1609 1609 D ShutdownThread: Notifying thread to start shutdown longPressBehavior=1
Line 302345: 05-02 05:03:17.288 1609 1609 D ShutdownThread: Attempting to use SysUI shutdown UI
Line 302346: 05-02 05:03:17.289 1609 1609 D ShutdownThread: SysUI handling shutdown UI
Line 302350: 05-02 05:03:17.300 1609 14282 I ShutdownThread: Sending shutdown broadcast…
Line 302404: 05-02 05:03:18.196 1609 14282 I ShutdownThread: Shutting down activity manager…
后面的Shutting down package manager并没有打印出来。
查看ShutdownThread.java：
Log.i(TAG, “Shutting down activity manager…”);
shutdownTimingLog.traceBegin(“ShutdownActivityManager”);
metricStarted(METRIC_AM);

    final IActivityManager am =
            IActivityManager.Stub.asInterface(ServiceManager.checkService("activity"));
    if (am != null) {
        try {
            am.shutdown(MAX_BROADCAS