SWT / anr issues - ams/wms

background ： some APP Frequent abnormal operations are easy to cause SWT problem , happen SWT The last two trace It may not be completely consistent , Such problems are easily manifested in ActivityManagerService and WindowManagerService in .

The analysis process

（ With WMS relayoutWindow For example ）

1. Confirm the problem time point (SYS_ANDROID_EVENT_LOG):

08-27 03:55:14.895  1481  1563 I watchdog: Blocked in handler on foreground thread (android.fg)

2. Find twice in the corresponding time period dump trace(SWT_JBT_TRACES)

1st dump:

"android.fg" Blocked -> "JobScheduler" Blocked -> "Binder:1481_1C" Blocked -> "Binder:1481_F" Blocked -> "Binder:1481_1B" Runnable

2nd dump:

"android.fg" Blocked -> "JobScheduler" Blocked -> "Binder:1481_1C" Blocked -> "Binder:1481_1D" Blocked -> "Binder:1481_D" Runnable

trace characteristic ：

two trace Very similar , But in the end block The threads are not the same , And in Runnable state , No explanation block live , It's just that some operations take too long , Leading to core services hang.<