We are seeming some behaviour on our deployed servers that hangs are causing a crash. We don’t actually set that value to true. Is there something that modifies this behaviour on shipping builds ? Our test builds only report hangs as errors on deployment.
Hi,
As far as I can see, nothing in the engine turns HangsAreFatal to true. The bHangsAreFatal default to false in D:\UE_5.4\Engine\Source\Runtime\Core\Private\HAL\ThreadHeartBeat.cpp:
FThreadHeartBeat::FThreadHeartBeat() : Thread(nullptr) ... , bHangsAreFatal(false) ... { It could be turned true if UE_ASSERT_ON_HANG was defined, but it default to 0 and I could not find a definition elsewhere.
#ifndef UE_ASSERT_ON_HANG #define UE_ASSERT_ON_HANG 0 #endifFinally, it can change in and Engine .ini file, but I didn’t find such definition in the engine code.
GConfig->GetBool(TEXT("Core.System"), TEXT("HangsAreFatal"), bNewHangsAreFatal, GEngineIni);Maybe you have this defined? It would be defined for some console by the engine, but it would not depend on the config (Test vs Shipping)
#define MINIMAL_FATAL_HANG_DETECTION (PLATFORM_USE_MINIMAL_HANG_DETECTION && 1)Otherwise, do you get a callstack/dump, or can you attach the debugger to the process and get exactly why it crashes? Debugging void FThreadHeartBeat::InitSettings() would tell you for sure what’s the value of bHangsAreFatal.
Regards,
Patrick
The crash happens in a shipped server already deployed. I don’t see it turned on after testing locally.
{"log":"[2025.04.30-01.31.08:278][298]LogCore: Error: Hang detected on GameThread (thread hasn't sent a heartbeat for 10.00 seconds):\n","stream":"stdout","time":"2025-04-30T01:31:08.278617027Z"} . . {"log":"[2025.04.30-01.31.08:278][298]LogCore: Error: 0x0000000008863b7e BelfryServer-Linux-Shipping!FEngineLoop::Tick() [D:/Stoic/work/9af7f4bc46f4c7b8/Engine/Source/./Runtime/Launch/Private/LaunchEngineLoop.cpp:5941]\n","stream":"stdout","time":"2025-04-30T01:31:08.279012944Z"} {"log":"sh: 1: xdg-user-dir: not found\n","stream":"stderr","time":"2025-04-30T01:31:08.46915813Z"} {"log":"[2025.04.30-01.31.08:278][298]LogCore: Error: 0x0000000008864b0a BelfryServer-Linux-Shipping!GuardedMain(char16_t const*) [D:/Stoic/work/9af7f4bc46f4c7b8/Engine/Source/./Runtime/Launch/PrivatLogPakFile: Initializing PakPlatformFile\n","stream":"stdout","time":"2025-04-30T01:31:08.611968952Z"} {"log":"LogPakFile: Display: Found Pak file ../../../Engine/Programs/CrashReportClient/Content/Paks/CrashReportClient.pak attempting to mount.\n","stream":"stdout","time":"2025-04-30T01:31:08.612025755Z"} . . . {"log":"[2025.04.30-01.31.10:629][ 0]LogCore: Engine exit requested (reason: CrashReportClientApp RequestExit)\n","stream":"stdout","time":"2025-04-30T01:31:10.632480247Z"} {"log":"[2025.04.30-01.31.10:629][ 0]LogExit: Preparing to exit.\n","stream":"stdout","time":"2025-04-30T01:31:10.632484747Z"} {"log":"[2025.04.30-01.31.10:630][ 0]LogExit: Object subsystem successfully closed.\n","stream":"stdout","time":"2025-04-30T01:31:10.632489047Z"} {"log":"[2025.04.30-01.31.10:631][ 0]LogPakFile: Destroying PakPlatformFile\n","stream":"stdout","time":"2025-04-30T01:31:10.667607004Z"} {"log":"[2025.04.30-01.31.10:633][ 0]LogExit: Exiting.\n","stream":"stdout","time":"2025-04-30T01:31:10.667691907Z"} {"log":"e/Launch.cpp:182]\n","stream":"stdout","time":"2025-04-30T01:31:10.672756817Z"} {"log":"[2025.04.30-01.31.08:278][298]LogCore: Error: 0x0000000008857c0b BelfryServer-Linux-Shipping!CommonUnixMain(int, char**, int (*)(char16_t const*), void (*)()) [D:/Stoic/work/9af7f4bc46f4c7b8/Engine/Source/./Runtime/Unix/UnixCommonStartup/Private/UnixCommonStartup.cpp:269]\n","stream":"stdout","time":"2025-04-30T01:31:10.672837521Z"} {"log":"[2025.04.30-01.31.08:278][298]LogCore: Error: 0x00007f5634238d90 libc.so.6!UnknownFunction(0x29d8f)\n","stream":"stdout","time":"2025-04-30T01:31:10.672879222Z"} {"log":"[2025.04.30-01.31.08:278][298]LogCore: Error: 0x00007f5634238e40 libc.so.6!__libc_start_main(+0x7f)\n","stream":"stdout","time":"2025-04-30T01:31:10.672883923Z"} {"log":"[2025.04.30-01.31.08:278][298]LogCore: Error: 0x000000000470a029 BelfryServer-Linux-Shipping!_start()\n","stream":"stdout","time":"2025-04-30T01:31:10.672888223Z"} {"log":"[2025.04.30-01.31.08:278][298]LogCore: Error: Hang detected on GameThread:\n","stream":"stdout","time":"2025-04-30T01:31:10.672892423Z"} {"log":" 0x0000000004957afa BelfryServer-Linux-Shipping!FUnixPlatformStackWalk::CaptureStackBackTrace(unsigned long long*, unsigned int, void*) [D:/Stoic/work/9af7f4bc46f4c7b8/Engine/Source/./Runtime/Core/Private/Unix/UnixPlatformStackWalk.cpp:765]\n","stream":"stdout","time":"2025-04-30T01:31:10.672896723Z"} {"log":" 0x000000000494465c BelfryServer-Linux-Shipping!ThreadStackWalker(int, siginfo_t*, void*) [D:/Stoic/work/9af7f4bc46f4c7b8/Engine/Source/./Runtime/Core/Private/Unix/UnixPlatformCrashContext.cpp:1060]\n","stream":"stdout","time":"2025-04-30T01:31:10.672901423Z"} {"log":" 0x00007f5634251520 libc.so.6!UnknownFunction(0x4251f)\n","stream":"stdout","time":"2025-04-30T01:31:10.672905824Z"} {"log":" 0x0000000004a42d27 BelfryServer-Linux-Shipping!FAsyncLoadingThread2::UpdateSyncLoadContext(FAsyncLoadingThreadState2\u0026, bool) [D:/Stoic/work/9af7f4bc46f4c7b8/Engine/Source/./Runtime/CoreUObject/Private/Serialization/AsyncLoading2.cpp:7638]\n","stream":"stdout","time":"2025-04-30T01:31:10.672910024Z"} {"log":"\n","stream":"stdout","time":"2025-04-30T01:31:10.672915924Z"} {"log":"Check log for full callstack.\n","stream":"stdout","time":"2025-04-30T01:31:10.672920224Z"} {"log":"Engine crash handling finished; re-raising signal 0 for the default handler. Good bye.\n","stream":"stdout","time":"2025-04-30T01:31:10.672924324Z"} {"log":"LogPakFile: Display: Mounting pak file ../../../Engine/Programs/CrashReportClient/Content/Paks/CrashReportClient.pak.\n","stream":"stdout","time":"2025-04-30T01:31:08.612030055Z"} {"log":"LogPakFile: Display: Mounted Pak file '../../../Engine/Programs/CrashReportClient/Content/Paks/CrashReportClient.pak', mount point: '../../../Engine/'\n","stream":"stdout","time":"2025-04-30T01:31:08.612033955Z"} {"log":"LogICUInternationalization: ICU TimeZone Detection - Raw Offset: +0:00, Platform Override: ''\n","stream":"stdout","time":"2025-04-30T01:31:08.612038355Z"}
The crash report client gets loaded right after the log about hang on the game thread. The hang is from some game code waiting for a background asset load to happen. The logs do read as if the crash is due to the hang. The signal 0 and reiteration of the Hang at the end.
I am asking internally to see if we turn it on somehow. But does not seem like it.
we caught a live instance of this today. The logs were cutting off and we assumed it was a crash. But looks like the process was just stuck. Thanks for the help.
Good, I’m glad this is sorted out. Let us know if you need something else!