9820E E516横屏项目，手机在使用过程中出现framework crash。通过log工具发现是
WATCHDOG KILLING SYSTEM PROCESS: Blocked in monitor com.android.server.am.ActivityManagerServiceEx on foreground thread (android.fg),
Blocked in handler on main thread (main),
Blocked in handler on WindowManager thread (WindowManager)。
WATCHDOG重启
然后main log 里面没有看到有效信息，
systemlog 里面
1-01 08:47:43.009 624 808 W Watchdog: *** WATCHDOG IS GOING TO KILL SYSTEM PROCESS: Blocked in monitor com.android.server.am.ActivityManagerServiceEx on foreground thread (android.fg), Blocked in handler on ActivityManager (ActivityManager), Blocked in handler on WindowManager thread (WindowManager)
01-01 08:47:43.009 624 808 D ActivityManager: dumpStackTraces begin
01-01 08:47:43.009 624 808 D ActivityManager: dumpStackTraces NATIVE_STACKS_OF_DEFAULT_PREDUMP pid 218
01-01 08:47:43.679 624 808 D ActivityManager: dumpStackTraces nativeProcs pid 197
01-01 08:47:43.789 624 808 D ActivityManager: dumpStackTraces nativeProcs pid 218
01-01 08:47:44.239 624 808 D ActivityManager: dumpStackTraces nativeProcs pid 224
01-01 08:47:45.029 624 808 D ActivityManager: dumpStackTraces firstPids(0) pid 624
01-01 08:47:47.839 624 808 D ActivityManager: dumpStackTraces NATIVE_STACKS_OF_DEFAULT pid 218
01-01 08:47:48.289 624 808 D ActivityManager: dumpStackTraces NATIVE_STACKS_OF_DEFAULT pid 224
01-01 08:47:49.099 624 808 D ActivityManager: dumpStackTraces end
01-01 08:47:49.099 624 808 W Watchdog: *** WATCHDOG after dumpStackTraces
01-01 08:47:52.109 624 808 W Watchdog: *** WATCHDOG after the second dumpKernelStackTraces
01-01 08:47:54.109 624 808 W Watchdog: *** WATCHDOG start addErrorToDropBox
01-01 08:47:54.489 624 808 W Watchdog: *** WATCHDOG end addErrorToDropBox
01-01 08:47:54.489 624 808 W Watchdog: *** WATCHDOG KILLING SYSTEM PROCESS: Blocked in monitor com.android.server.am.ActivityManagerServiceEx on foreground thread (android.fg), Blocked in handler on ActivityManager (ActivityManager), Blocked in handler on WindowManager thread (WindowManager)
01-01 08:47:54.489 624 808 W Watchdog: foreground thread stack trace:
01-01 08:47:54.489 624 808 W Watchdog: at com.android.server.am.ActivityManagerService.monitor(ActivityManagerService.java:16858)
01-01 08:47:54.489 624 808 W Watchdog: at com.android.server.Watchdog$HandlerChecker.run(Watchdog.java:192)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.Handler.handleCallback(Handler.java:733)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.Handler.dispatchMessage(Handler.java:95)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.Looper.loop(Looper.java:136)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.HandlerThread.run(HandlerThread.java:61)
01-01 08:47:54.489 624 808 W Watchdog: ActivityManager stack trace:
01-01 08:47:54.489 624 808 W Watchdog: at com.android.server.am.ActiveServices$ServiceMap.handleMessage(ActiveServices.java:185)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.Handler.dispatchMessage(Handler.java:102)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.Looper.loop(Looper.java:136)
01-01 08:47:54.489 624 808 W Watchdog: at com.android.server.am.ActivityManagerService$AThread.run(ActivityManagerService.java:2006)
01-01 08:47:54.489 624 808 W Watchdog: WindowManager thread stack trace:
01-01 08:47:54.489 624 808 W Watchdog: at com.android.server.wm.WindowManagerService$H.handleMessage(WindowManagerService.java:7486)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.Handler.dispatchMessage(Handler.java:102)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.Looper.loop(Looper.java:136)
01-01 08:47:54.489 624 808 W Watchdog: at android.os.HandlerThread.run(HandlerThread.java:61)
01-01 08:47:54.489 624 808 W Watchdog: *** GOODBYE!
以为没有价值
（从目前查到的凶手是WindowManagerService看，这个信息是有价值的，提到的几个service都应该检查是否有耗时操作）
然后进行各种联想还原，发现无效，最后发现这个和ANR是一样的，有用的信息都在traces.log里面，有记录当前卡在哪里了
顺序查找，看下是否有修改的耗时的地方。就能发现问题了，
当前我们后行添加的修改是在 at com.android.server.wm.WindowManagerService.getActivity(WindowManagerService.java:5968)
（当前手机特殊为横屏手机，微信应用在这个几面显示旋转了，研发在这个类里面通过判断顶层应用是否为微信，强制进行了旋转使其正常，产生问题）
跟log吻合
"Binder_1" prio=5 tid=9 MONITOR
| group="main" sCount=1 dsCount=0 obj=0x41821bf0 self=0x80e44688
| sysTid=653 nice=0 sched=0/0 cgrp=apps handle=-2132523968
| state=S schedstat=( 420131427 522294460 1825 ) utm=20 stm=22 core=1
at com.android.server.am.ActivityManagerService.getTasks(ActivityManagerService.java:~7225)
- waiting to lock <0x4182a3f8> (a com.android.server.am.ActivityManagerServiceEx) held by tid=64 (Binder_9)
at android.app.ActivityManager.getRunningTasks(ActivityManager.java:785)
at android.app.ActivityManager.getRunningTasks(ActivityManager.java:821)
at com.android.server.wm.WindowManagerService.getActivity(WindowManagerService.java:5968)
at com.android.server.wm.WindowManagerService.updateRotationUncheckedLocked(WindowManagerService.java:6030)
at com.android.server.wm.WindowManagerService.updateOrientationFromAppTokensLocked(WindowManagerService.java:3735)
at com.android.server.wm.WindowManagerService.relayoutWindow(WindowManagerService.java:3043)
at com.android.server.wm.Session.relayout(Session.java:190)
at android.view.IWindowSession$Stub.onTransact(IWindowSession.java:235)
at com.android.server.wm.Session.onTransact(Session.java:125)
at android.os.Binder.execTransact(Binder.java:427)
at dalvik.system.NativeStart.run(Native Method)
log里同样发现 at com.android.internal.policy.impl.PhoneWindowManager.getTopActivity(PhoneWindowManager.java:4255) 应该也是有隐患的。
"InputDispatcher" prio=10 tid=30 MONITOR
| group="main" sCount=1 dsCount=0 obj=0x419556a8 self=0x81726e48
| sysTid=710 nice=-8 sched=0/0 cgrp=apps handle=-2123208264
| state=S schedstat=( 1637991276 961247664 12418 ) utm=95 stm=68 core=0
at com.android.server.am.ActivityManagerService.getTasks(ActivityManagerService.java:~7225)
- waiting to lock <0x417eb3f8> (a com.android.server.am.ActivityManagerServiceEx) held by tid=59 (Binder_5)
at android.app.ActivityManager.getRunningTasks(ActivityManager.java:785)
at android.app.ActivityManager.getRunningTasks(ActivityManager.java:821)
at com.android.internal.policy.impl.PhoneWindowManager.getTopActivity(PhoneWindowManager.java:4255)
at com.android.internal.policy.impl.PhoneWindowManager.interceptKeyBeforeDispatching(PhoneWindowManager.java:2481)
at com.android.server.wm.InputMonitor.interceptKeyBeforeDispatching(InputMonitor.java:382)
at com.android.server.input.InputManagerService.interceptKeyBeforeDispatching(InputManagerService.java:1353)
at dalvik.system.NativeStart.run(Native Method)
从上面log看和历史出现问题 以下getTopActivity（）方法（Android4.4做状态栏待机透明和非待机黑色判断是否为待机界面也使用了这个方法，出现过null的问题切换黑屏）不建议在系统级别常用服务或者类中操作
public String getActivity(){
ActivityManager manager = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> runningTaskInfos = manager.getRunningTasks(1);
if (runningTaskInfos != null)
return runningTaskInfos.get(0).topActivity.getClassName();
else
return null;
}
经验：Watchdog现象先看traces.log
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