[4.14.3] Random Hard Lock/Stall on Gamethread

Hi there,

I’m streaming in levels, on a GameThread-spawned task graph thread. This has been working fine thus far, but we’re now getting seemingly random hard locks on the Gamethread. Our Level spawning thread, along with the FMOD threads still seem to be running normally. However the game gets stuck on the tick.

Below is the call stack of the stall:

 	FreeTheNetwork-Win64-DebugGame.exe!FEventWin::Wait(unsigned int WaitTime, const bool bIgnoreThreadIdleStats) Line 1061	C++
 	FreeTheNetwork-Win64-DebugGame.exe!FNamedTaskThread::Stall(int QueueIndex, TStatId StallStatId, bool bCountAsStall) Line 1099	C++
>	FreeTheNetwork-Win64-DebugGame.exe!FNamedTaskThread::ProcessTasksNamedThread(int QueueIndex, bool bAllowStall) Line 890	C++
 	FreeTheNetwork-Win64-DebugGame.exe!FNamedTaskThread::ProcessTasksUntilQuit(int QueueIndex) Line 679	C++
 	FreeTheNetwork-Win64-DebugGame.exe!FTaskGraphImplementation::WaitUntilTasksComplete(const TArray<TRefCountPtr<FGraphEvent>,TInlineAllocator<4,FDefaultAllocator> > & Tasks, ENamedThreads::Type CurrentThreadIfKnown) Line 1776	C++
 	FreeTheNetwork-Win64-DebugGame.exe!FTickTaskSequencer::ReleaseTickGroup(ETickingGroup WorldTickGroup, bool bBlockTillComplete) Line 525	C++
 	FreeTheNetwork-Win64-DebugGame.exe!FTickTaskManager::RunTickGroup(ETickingGroup Group, bool bBlockTillComplete) Line 1437	C++
 	FreeTheNetwork-Win64-DebugGame.exe!UWorld::RunTickGroup(ETickingGroup Group, bool bBlockTillComplete) Line 730	C++
 	FreeTheNetwork-Win64-DebugGame.exe!UWorld::Tick(ELevelTick TickType, float DeltaSeconds) Line 1357	C++
 	FreeTheNetwork-Win64-DebugGame.exe!UGameEngine::Tick(float DeltaSeconds, bool bIdleMode) Line 1123	C++
 	FreeTheNetwork-Win64-DebugGame.exe!FEngineLoop::Tick() Line 2859	C++
 	FreeTheNetwork-Win64-DebugGame.exe!GuardedMain(const wchar_t * CmdLine, HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, int nCmdShow) Line 152	C++
 	FreeTheNetwork-Win64-DebugGame.exe!WinMain(HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, char * __formal, int nCmdShow) Line 191	C++

Any one encountered this before, or have any ideas on what may be the cause?

Thanks!
.