Hello,
I have recently discovered a reproducible hitch in my project and am unable to trace its source.
After doing a week’s worth of debugging I have discovered the hitch is coming from the render thread and is happening mainly because of Hello,
I have recently discovered a reproducible hitch in my project and am unable to trace its source.
After doing a week’s worth of debugging I have discovered the hitch is coming from the render thread and is happening mainly because of MeshPassSetupImmediate and SetupMeshPass.
And… that’s it, I couldn’t find a more specific hint as to what element is causing the issue.
I am attaching a ue4stats file highlighting the spike in hope for an answer or a hint for one.
Here is the ue4stats file
And here is the DumpHitchs part of the log:
EDIT: I have found out an old bug report that describes my issue, its code is UE-76006.
[2020.08.19-11.00.16:055][414]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.16:064][415]LogStats: ------------------Thread Hitch 1, Frame 414 76.8ms ---------------
[2020.08.19-11.00.16:064][415]LogStats: Warning: There is no thread with id: 1031. Please add thread metadata for this thread.
[2020.08.19-11.00.16:064][415]LogStats: ------------------ Game Thread 76.78ms
[2020.08.19-11.00.16:064][415]LogStats: 76.642ms ( 4) - Thread_a807_0 - GameThread - STATGROUP_Threads - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 76.567ms ( 2) - FrameTime - STAT_FrameTime - STATGROUP_Engine - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 70.804ms ( 1) - Frame Sync Time - STAT_FrameSyncTime - STATGROUP_Engine - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 70.638ms ( 1) - Game thread idle time - STAT_GameIdleTime - STATGROUP_Threading - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 70.102ms ( 38) - CPU Stall - Wait For Event - STAT_EventWait - STATGROUP_CPUStalls - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 0.536ms ( 115) - OtherChildren
[2020.08.19-11.00.16:064][415]LogStats: 0.166ms ( 4) - OtherChildren
[2020.08.19-11.00.16:064][415]LogStats: 4.990ms ( 1) - GameEngine Tick - STAT_GameEngineTick - STATGROUP_Engine - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 2.119ms ( 1) - TickAsyncLoading GT - STAT_FAsyncPackage_TickAsyncLoadingGameThread - STATGROUP_AsyncLoadGameThread - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 2.096ms ( 1) - Self
[2020.08.19-11.00.16:064][415]LogStats: 0.022ms ( 3) - OtherChildren
[2020.08.19-11.00.16:064][415]LogStats: 1.493ms ( 14) - OtherChildren
[2020.08.19-11.00.16:064][415]LogStats: 1.378ms ( 1) - World Tick Time - STAT_WorldTickTime - STATGROUP_Game - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 1.133ms ( 6) - Tick Time - STAT_TickTime - STATGROUP_Game - STATCAT_Advanced
[2020.08.19-11.00.16:064][415]LogStats: 1.133ms ( 21) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 0.245ms ( 13) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 0.774ms ( 19) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 0.075ms ( 2) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: ------------------ Render Thread (//STATGROUP_Threads//RenderThread///Thread_15317_0///####STATCAT_Advanced####) 8.97ms
[2020.08.19-11.00.16:065][415]LogStats: 8.914ms ( 37) - Thread_15317_0 - RenderThread - STATGROUP_Threads - STATCAT_Advanced
[2020.08.19-11.00.16:065][415]LogStats: 4.837ms ( 1) - SlateDrawWindowsCommand - STATGROUP_RenderThreadCommands - STATCAT_Advanced
[2020.08.19-11.00.16:065][415]LogStats: 4.546ms ( 1) - CPU Stall - Wait For Event - STAT_EventWait - STATGROUP_CPUStalls - STATCAT_Advanced
[2020.08.19-11.00.16:065][415]LogStats: 0.291ms ( 4) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 2.298ms ( 1) - FDrawSceneCommand - STATGROUP_RenderThreadCommands - STATCAT_Advanced
[2020.08.19-11.00.16:065][415]LogStats: 2.275ms ( 1) - RenderViewFamily - STAT_TotalSceneRenderingTime - STATGROUP_SceneRendering - STATCAT_Advanced
[2020.08.19-11.00.16:065][415]LogStats: 2.181ms ( 1) - STAT_FMobileSceneRenderer_Render - STATGROUP_Quick - STATCAT_Advanced
[2020.08.19-11.00.16:065][415]LogStats: 1.140ms ( 11) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 1.041ms ( 1) - FinishRenderViewTarget - STAT_FinishRenderViewTargetTime - STATGROUP_SceneRendering - STATCAT_Advanced
[2020.08.19-11.00.16:065][415]LogStats: 1.041ms ( 12) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 0.094ms ( 6) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 0.023ms ( 4) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 1.203ms ( 1) - AvfMediaVideoSamplerTick - STATGROUP_RenderThreadCommands - STATCAT_Advanced
[2020.08.19-11.00.16:065][415]LogStats: 1.166ms ( 1) - Self
[2020.08.19-11.00.16:065][415]LogStats: 0.037ms ( 3) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: 0.576ms ( 34) - OtherChildren
[2020.08.19-11.00.16:065][415]LogStats: ----------------------------------------
[2020.08.19-11.00.16:065][415]LogStats: Events history: Single frame 414, greater than 1.0 ms
[2020.08.19-11.00.16:065][415]LogStats: Displaying events history for GameThread
[2020.08.19-11.00.16:066][415]LogStats: Displaying events history for RenderThread
[2020.08.19-11.00.16:066][415]LogStats: ----------------------------------------
[2020.08.19-11.00.16:130][415]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.16:153][415]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.16:201][415]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.16:249][415]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.16:297][415]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.16:349][416]LogStats: Warning: There is no thread with id: 49411. Please add thread metadata for this thread.
[2020.08.19-11.00.16:408][419]LogStats: Warning: There is no thread with id: 32011. Please add thread metadata for this thread.
[2020.08.19-11.00.21:438][721]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.21:559][721]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.21:579][721]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.21:694][721]LogMetal: Display: Loaded a text shader (will be slower to load)
[2020.08.19-11.00.21:766][722]LogStats: ------------------Thread Hitch 2, Frame 721 320.8ms ---------------
[2020.08.19-11.00.21:766][722]LogStats: ------------------ Game Thread 16.48ms
[2020.08.19-11.00.21:766][722]LogStats: 16.297ms ( 4) - Thread_a807_0 - GameThread - STATGROUP_Threads - STATCAT_Advanced
[2020.08.19-11.00.21:766][722]LogStats: 16.269ms ( 2) - FrameTime - STAT_FrameTime - STATGROUP_Engine - STATCAT_Advanced
[2020.08.19-11.00.21:766][722]LogStats: 13.068ms ( 1) - Frame Sync Time - STAT_FrameSyncTime - STATGROUP_Engine - STATCAT_Advanced
[2020.08.19-11.00.21:766][722]LogStats: 13.057ms ( 1) - Game thread idle time - STAT_GameIdleTime - STATGROUP_Threading - STATCAT_Advanced
[2020.08.19-11.00.21:766][722]LogStats: 13.004ms ( 9) - CPU Stall - Wait For Event - STAT_EventWait - STATGROUP_CPUStalls - STATCAT_Advanced
[2020.08.19-11.00.21:766][722]LogStats: 0.053ms ( 28) - OtherChildren
[2020.08.19-11.00.21:766][722]LogStats: 0.011ms ( 4) - OtherChildren
[2020.08.19-11.00.21:766][722]LogStats: 2.534ms ( 1) - GameEngine Tick - STAT_GameEngineTick - STATGROUP_Engine - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 1.349ms ( 15) - OtherChildren
[2020.08.19-11.00.21:767][722]LogStats: 1.185ms ( 1) - World Tick Time - STAT_WorldTickTime - STATGROUP_Game - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 1.185ms ( 19) - OtherChildren
[2020.08.19-11.00.21:767][722]LogStats: 0.667ms ( 19) - OtherChildren
[2020.08.19-11.00.21:767][722]LogStats: 0.028ms ( 2) - OtherChildren
[2020.08.19-11.00.21:767][722]LogStats: ------------------ Render Thread (//STATGROUP_Threads//RenderThread///Thread_15317_0///####STATCAT_Advanced####) 320.76ms
[2020.08.19-11.00.21:767][722]LogStats: 320.671ms ( 72) - Thread_15317_0 - RenderThread - STATGROUP_Threads - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 318.683ms ( 1) - FDrawSceneCommand - STATGROUP_RenderThreadCommands - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 318.650ms ( 1) - RenderViewFamily - STAT_TotalSceneRenderingTime - STATGROUP_SceneRendering - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 318.220ms ( 1) - STAT_FMobileSceneRenderer_Render - STATGROUP_Quick - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 273.391ms ( 1) - InitViews - STAT_InitViewsTime - STATGROUP_SceneRendering - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 140.109ms ( 1) - View Visibility - STAT_ViewVisibilityTime - STATGROUP_InitViews - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 139.922ms ( 1) - SetupMeshPass - STAT_SetupMeshPass - STATGROUP_InitViews - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 139.909ms ( 1) - STAT_MeshPassSetupImmediate - STATGROUP_Quick - STATCAT_Advanced
[2020.08.19-11.00.21:767][722]LogStats: 139.767ms ( 1) - Self
[2020.08.19-11.00.21:767][722]LogStats: 0.142ms ( 8) - OtherChildren
[2020.08.19-11.00.21:768][722]LogStats: 0.013ms ( 1) - OtherChildren
[2020.08.19-11.00.21:768][722]LogStats: 0.187ms ( 10) - OtherChildren
[2020.08.19-11.00.21:768][722]LogStats: 133.075ms ( 1) - STAT_MeshPassSetupImmediate - STATGROUP_Quick - STATCAT_Advanced
[2020.08.19-11.00.21:768][722]LogStats: 132.983ms ( 1) - Self
[2020.08.19-11.00.21:768][722]LogStats: 0.092ms ( 8) - OtherChildren
[2020.08.19-11.00.21:768][722]LogStats: 0.207ms ( 10) - OtherChildren
[2020.08.19-11.00.21:768][722]LogStats: 21.805ms ( 1) - Base pass drawing - STAT_BasePassDrawTime - STATGROUP_SceneRendering - STATCAT_Advanced
[2020.08.19-11.00.21:768][722]LogStats: 21.777ms ( 1) - STAT_MeshPassDrawImmediate - STATGROUP_Quick - STATCAT_Advanced
[2020.08.19-11.00.21:768][722]LogStats: 21.614ms ( 3) - PipelineState time - STAT_MetalPipelineStateTime - STATGROUP_MetalRHI - STATCAT_Advanced
[2020.08.19-11.00.21:768][722]LogStats: 0.163ms ( 3) - OtherChildren
[2020.08.19-11.00.21:768][722]LogStats: 0.028ms ( 2) - OtherChildren
[2020.08.19-11.00.21:768][722]LogStats: 21.510ms ( 1) - Translucency drawing - STAT_TranslucencyDrawTime - STATGROUP_SceneRendering - STATCAT_Advanced
[2020.08.19-11.00.21:773][723]LogStats: 21.490ms ( 1) - STAT_MeshPassDrawImmediate - STATGROUP_Quick - STATCAT_Advanced
[2020.08.19-11.00.21:773][723]LogStats: 21.341ms ( 3) - PipelineState time - STAT_MetalPipelineStateTime - STATGROUP_MetalRHI - STATCAT_Advanced
[2020.08.19-11.00.21:773][723]LogStats: 0.149ms ( 7) - OtherChildren
[2020.08.19-11.00.21:773][723]LogStats: 0.020ms ( 1) - OtherChildren
[2020.08.19-11.00.21:773][723]LogStats: 1.105ms ( 1) - FinishRenderViewTarget - STAT_FinishRenderViewTargetTime - STATGROUP_SceneRendering - STATCAT_Advanced
[2020.08.19-11.00.21:773][723]LogStats: 1.105ms ( 12) - OtherChildren
[2020.08.19-11.00.21:773][723]LogStats: 0.409ms ( 6) - OtherChildren
[2020.08.19-11.00.21:773][723]LogStats: 0.431ms ( 6) - OtherChildren
[2020.08.19-11.00.21:773][723]LogStats: 0.032ms ( 4) - OtherChildren
[2020.08.19-11.00.21:773][723]LogStats: 1.206ms ( 1) - AvfMediaVideoSamplerTick - STATGROUP_RenderThreadCommands - STATCAT_Advanced
[2020.08.19-11.00.21:773][723]LogStats: 1.175ms ( 1) - Self
[2020.08.19-11.00.21:773][723]LogStats: 0.031ms ( 3) - OtherChildren
[2020.08.19-11.00.21:773][723]LogStats: 0.782ms ( 70) - OtherChildren
[2020.08.19-11.00.21:774][723]LogStats: ----------------------------------------
[2020.08.19-11.00.21:774][723]LogStats: Events history: Single frame 721, greater than 1.0 ms
[2020.08.19-11.00.21:774][723]LogStats: Displaying events history for GameThread
[2020.08.19-11.00.21:774][723]LogStats: Duration: 12.89 MS
[2020.08.19-11.00.21:774][723]LogStats: Wait : Game thread idle time <- Frame Sync Time <- FrameTime <- GameThread
[2020.08.19-11.00.21:774][723]LogStats: Trigger: FTriggerEventGraphTask <- RenderThread
[2020.08.19-11.00.21:774][723]LogStats: Displaying events history for RenderThread
[2020.08.19-11.00.21:774][723]LogStats: ----------------------------------------