Unit test deadlock during xUnit Shutdown

[jasonmalinowski]

This was hit in a CI run. The unit test shutdown of the AppDomain hung here:

 	clr.dll!MsgWaitHelper(int numWaiters, void * * phEvent, int bWaitAll, unsigned long millis, int bAlertable) Line 4258	C++
 	[Inline Frame] clr.dll!Thread::DoAppropriateAptStateWait(int) Line 4323	C++
 	clr.dll!Thread::DoAppropriateWaitWorker(int countHandles, void * * handles, int waitAll, unsigned long millis, WaitMode mode) Line 4468	C++
 	clr.dll!Thread::DoAppropriateWait(int countHandles, void * * handles, int waitAll, unsigned long millis, WaitMode mode, PendingSync * syncState) Line 4135	C++
 	[Inline Frame] clr.dll!SOIntolerantTransitionHandler::SetNoException() Line 853	C++
 	clr.dll!CLREventBase::WaitEx(unsigned long dwMilliseconds, WaitMode mode, PendingSync * syncState) Line 849	C++
 	clr.dll!AppDomain::UnloadWait(ADID Id, ADUnloadSink * pSink) Line 11187	C++
 	clr.dll!AppDomain::UnloadById(ADID dwId, int fSync, int) Line 11166	C++
 	clr.dll!AppDomainNative::Unload(int dwId) Line 1235	C++

[jasonmalinowski]

Failed run was here. Dump has been copied to \\mlangfs1\public\jasonmal\Dumps\Roslyn\40369.

[sharwell]

I hit this today as well. Looks like it's blocked in COM code.

[jasonmalinowski]

Yeah, it's blocked in some COM wait, but I had no idea what it was doing.

[JoeRobich]

Hit this again in Attempt #1