#include "RenderingThread.h"
#include "HAL/Runnable.h"
#include "HAL/RunnableThread.h"
#include "HAL/ExceptionHandling.h"
#include "HAL/PlatformApplicationMisc.h"
#include "Misc/App.h"
#include "Misc/CommandLine.h"
#include "Misc/OutputDeviceRedirector.h"
#include "Misc/CoreStats.h"
#include "Misc/TimeGuard.h"
#include "Misc/CoreDelegates.h"
#include "Misc/ScopeLock.h"
#include "RHI.h"
#include "RenderCore.h"
#include "RenderCommandFence.h"
#include "RenderDeferredCleanup.h"
#include "TickableObjectRenderThread.h"
#include "Stats/StatsSystem.h"
#include "Stats/StatsData.h"
#include "HAL/ThreadHeartBeat.h"
#include "RenderResource.h"
#include "RHIUtilities.h"
#include "HAL/LowLevelMemTracker.h"
#include "ProfilingDebugging/MiscTrace.h"
#include "ProfilingDebugging/CsvProfiler.h"
#include "Async/TaskTrace.h"
#include "DataDrivenShaderPlatformInfo.h"
#include "HAL/ThreadManager.h"
#include "ProfilingDebugging/CountersTrace.h"
#include "Async/ParallelFor.h"

Classes
class	FRHIThread

class	FRenderingThread

struct	FSuspendRenderingTickables

class	FRenderingThreadTickHeartbeat

struct	FConsoleRenderThreadPropagation

struct	FRenderCommandFenceBundlerState

class	FRenderCommandPipeRegistry

Namespaces
namespace	UE

namespace	UE::RenderCommandPipe

namespace	FFrameEndSync

Macros
#define	UE_RENDER_COMMAND_FENCE_BUNDLER_REGION TEXT("Render Command Fence Bundler")

#define	UE_RENDER_COMMAND_PIPE_RECORD_REGION TEXT("Render Command Pipe Recording")

#define	UE_RENDER_COMMAND_PIPE_SYNC_REGION TEXT("Render Command Pipe Synced")

#define	UE_RENDER_COMMAND_BEGIN_REGION(Region)

#define	UE_RENDER_COMMAND_END_REGION(Region)

Functions
	UE_TRACE_CHANNEL_DEFINE (RenderCommandsChannel)

RENDERCORE_API TAtomic< bool >	GMainThreadBlockedOnRenderThread (false)

ERenderCommandPipeMode	GetValidatedRenderCommandPipeMode (int32 CVarValue)

void	RenderingThreadMain (FEvent *TaskGraphBoundSyncEvent)

void	AdvanceRenderingThreadStatsGT (bool bDiscardCallstack, int64 StatsFrame, int32 DisableChangeTagStartFrame)

FDelegateHandle	RegisterStopRenderingThreadDelegate (const FStopRenderingThread::FDelegate &InDelegate)

void	UnregisterStopRenderingThreadDelegate (FDelegateHandle InDelegateHandle)

RENDERCORE_API void	LatchRenderThreadConfiguration ()

RENDERCORE_API void	InitRenderingThread ()

RENDERCORE_API void	ShutdownRenderingThread ()

void	CheckRenderingThreadHealth ()

bool	IsRenderingThreadHealthy ()

void	StartRenderCommandFenceBundler ()

void	FlushRenderCommandFenceBundler ()

void	StopRenderCommandFenceBundler ()

void	SuspendRenderThreadTimeout ()

void	ResumeRenderThreadTimeout ()

bool	IsRenderThreadTimeoutSuspended ()

void	FlushRenderingCommands ()

void	FlushPendingDeleteRHIResources_GameThread ()

void	FlushPendingDeleteRHIResources_RenderThread ()

FRHICommandListImmediate &	GetImmediateCommandList_ForRenderCommand ()

void	BeginCleanup (FDeferredCleanupInterface *CleanupObject)

FPendingCleanupObjects *	GetPendingCleanupObjects ()

	DECLARE_RENDER_COMMAND_TAG (FRenderCommandTag_ExecuteCommandLists, ExecuteCommandLists)

bool	HasBitsSet (const FRenderCommandPipeBitArray &Bits)

	DECLARE_CYCLE_STAT (TEXT("Frame Sync Time"), STAT_FrameSyncTime, STATGROUP_RenderThreadProcessing)

Variables
RENDERCORE_API bool	GIsThreadedRendering = false

RENDERCORE_API bool	GUseThreadedRendering = false

RENDERCORE_API TOptional< bool >	GPendingUseThreadedRendering

FString	GRenderingThreadError

volatile bool	GIsRenderingThreadHealthy = true

float	GRenderingThreadMaxIdleTickFrequency = 40.f

CORE_API bool	GRenderThreadPollingOn

CORE_API int32	GRenderThreadPollPeriodMs

bool	GRenderCommandFenceBundling = true

FAutoConsoleVariableRef	CVarRenderCommandFenceBundling (TEXT("r.RenderCommandFenceBundling"), GRenderCommandFenceBundling, TEXT(" 1: enabled (default);\n"), ECVF_Default)

ERenderCommandPipeMode	GRenderCommandPipeMode = ERenderCommandPipeMode::None

FAutoConsoleVariable	CVarRenderCommandPipeMode (TEXT("r.RenderCommandPipeMode"), 2, TEXT(" 2: Render commands are enqueued into a render command pipe for all declared pipes.;\n"), FConsoleVariableDelegate::CreateLambda([](IConsoleVariable *Variable) { UE::RenderCommandPipe::StopRecording();GRenderCommandPipeMode=GetValidatedRenderCommandPipeMode(Variable->GetInt());}))

uint32	GRenderThreadTime = 0

uint32	GRenderThreadWaitTime = 0

uint32	GRHIThreadTime = 0

uint32	GRenderThreadTimeCriticalPath = 0

FRHIThread *	GRHIThread = nullptr

TAtomic< bool >	GRunRenderingThreadHeartbeat

FThreadSafeCounter	OutstandingHeartbeats

TAtomic< int32 >	GSuspendRenderingTickables

FRunnableThread *	GRenderingThreadHeartbeat = NULL

FRunnable *	GRenderingThreadRunnableHeartbeat = NULL

std::atomic< int >	GTimeoutSuspendCount

uint32	GGameThreadTime = 0

uint32	GGameThreadWaitTime = 0

uint32	GGameThreadTimeCriticalPath = 0

uint32	GSwapBufferTime = 0

TAutoConsoleVariable< int32 >	CVarAllowOneFrameThreadLag (TEXT("r.OneFrameThreadLag"), 1,)

TAutoConsoleVariable< int32 >	CVarGTSyncType (TEXT("r.GTSyncType"), 0, TEXT(" <= 0 - Sync the game thread with the N-1 render thread frame. Then sync with the N-m RHI thread frame where m is (2 + (-r.GTSyncType)) (i.e. negative values increase the amount of RHI thread overlap) (default = 0).\n") TEXT(" 2 - Sync the game thread with the GPU swap chain flip (only on supported platforms).\n"), ECVF_Default)

Macro Definition Documentation

◆ UE_RENDER_COMMAND_BEGIN_REGION

#define UE_RENDER_COMMAND_BEGIN_REGION ( Region )

◆ UE_RENDER_COMMAND_END_REGION

#define UE_RENDER_COMMAND_END_REGION ( Region )

◆ UE_RENDER_COMMAND_FENCE_BUNDLER_REGION

#define UE_RENDER_COMMAND_FENCE_BUNDLER_REGION TEXT("Render Command Fence Bundler")

◆ UE_RENDER_COMMAND_PIPE_RECORD_REGION

#define UE_RENDER_COMMAND_PIPE_RECORD_REGION TEXT("Render Command Pipe Recording")

◆ UE_RENDER_COMMAND_PIPE_SYNC_REGION

#define UE_RENDER_COMMAND_PIPE_SYNC_REGION TEXT("Render Command Pipe Synced")

Function Documentation

◆ AdvanceRenderingThreadStatsGT()

void AdvanceRenderingThreadStatsGT	(	bool	bDiscardCallstack,
		int64	StatsFrame,
		int32	DisableChangeTagStartFrame
	)

Advances stats for the rendering thread. Called from the game thread.

◆ BeginCleanup()

void BeginCleanup ( FDeferredCleanupInterface * CleanupObject )

Adds the specified deferred cleanup object to the current set of pending cleanup objects.

◆ CheckRenderingThreadHealth()

void CheckRenderingThreadHealth ( )

Checks if the rendering thread is healthy and running. If it has crashed, UE_LOG is called with the exception information.

◆ DECLARE_CYCLE_STAT()

DECLARE_CYCLE_STAT	(	TEXT("Frame Sync Time")	,
		STAT_FrameSyncTime	,
		STATGROUP_RenderThreadProcessing
	)

◆ DECLARE_RENDER_COMMAND_TAG()

DECLARE_RENDER_COMMAND_TAG	(	FRenderCommandTag_ExecuteCommandLists	,
		ExecuteCommandLists
	)

◆ FlushPendingDeleteRHIResources_GameThread()

void FlushPendingDeleteRHIResources_GameThread ( )

◆ FlushPendingDeleteRHIResources_RenderThread()

void FlushPendingDeleteRHIResources_RenderThread ( )

◆ FlushRenderCommandFenceBundler()

void FlushRenderCommandFenceBundler ( )

◆ FlushRenderingCommands()

void FlushRenderingCommands ( )

Waits for the rendering thread to finish executing all pending rendering commands. Should only be used from the game thread.

◆ GetImmediateCommandList_ForRenderCommand()

FRHICommandListImmediate & GetImmediateCommandList_ForRenderCommand ( )

◆ GetPendingCleanupObjects()

FPendingCleanupObjects * GetPendingCleanupObjects ( )

Transfers ownership of the current set of pending cleanup objects to the caller. A new set is created for subsequent BeginCleanup calls.

Returns: A pointer to the set of pending cleanup objects. The called is responsible for deletion.

◆ GetValidatedRenderCommandPipeMode()

ERenderCommandPipeMode GetValidatedRenderCommandPipeMode ( int32 CVarValue )

inline

◆ GMainThreadBlockedOnRenderThread()

RENDERCORE_API TAtomic< bool > GMainThreadBlockedOnRenderThread ( false )

◆ HasBitsSet()

bool HasBitsSet ( const FRenderCommandPipeBitArray & Bits )

inline

◆ InitRenderingThread()

RENDERCORE_API void InitRenderingThread ( )

◆ IsRenderingThreadHealthy()

bool IsRenderingThreadHealthy ( )

Checks if the rendering thread is healthy and running, without crashing

◆ IsRenderThreadTimeoutSuspended()

bool IsRenderThreadTimeoutSuspended ( )

◆ LatchRenderThreadConfiguration()

RENDERCORE_API void LatchRenderThreadConfiguration ( )

◆ RegisterStopRenderingThreadDelegate()

FDelegateHandle RegisterStopRenderingThreadDelegate ( const FStopRenderingThread::FDelegate & InDelegate )

◆ RenderingThreadMain()

void RenderingThreadMain ( FEvent * TaskGraphBoundSyncEvent )

The rendering thread main loop

◆ ResumeRenderThreadTimeout()

void ResumeRenderThreadTimeout ( )

◆ ShutdownRenderingThread()

RENDERCORE_API void ShutdownRenderingThread ( )

◆ StartRenderCommandFenceBundler()

void StartRenderCommandFenceBundler ( )

◆ StopRenderCommandFenceBundler()

void StopRenderCommandFenceBundler ( )

◆ SuspendRenderThreadTimeout()

void SuspendRenderThreadTimeout ( )

◆ UE_TRACE_CHANNEL_DEFINE()

UE_TRACE_CHANNEL_DEFINE ( RenderCommandsChannel )

◆ UnregisterStopRenderingThreadDelegate()

void UnregisterStopRenderingThreadDelegate ( FDelegateHandle InDelegateHandle )

Variable Documentation

◆ CVarAllowOneFrameThreadLag

TAutoConsoleVariable< int32 > CVarAllowOneFrameThreadLag(TEXT("r.OneFrameThreadLag"), 1,)	(	TEXT("r.OneFrameThreadLag")	,
		1
	)

◆ CVarGTSyncType

TAutoConsoleVariable< int32 > CVarGTSyncType(TEXT("r.GTSyncType"), 0, TEXT(" <= 0 - Sync the game thread with the N-1 render thread frame. Then sync with the N-m RHI thread frame where m is (2 + (-r.GTSyncType)) (i.e. negative values increase the amount of RHI thread overlap) (default = 0).\n") TEXT(" 2 - Sync the game thread with the GPU swap chain flip (only on supported platforms).\n"), ECVF_Default)	(	TEXT("r.GTSyncType")	,
		0	,
		TEXT(" <= 0 - Sync the game thread with the N-1 render thread frame. Then sync with the N-m RHI thread frame where m is (2 + (-r.GTSyncType)) (i.e. negative values increase the amount of RHI thread overlap) (default = 0).\n") TEXT(" 2 - Sync the game thread with the GPU swap chain flip (only on supported platforms).\n")	,
		ECVF_Default
	)

◆ CVarRenderCommandFenceBundling

FAutoConsoleVariableRef CVarRenderCommandFenceBundling(TEXT("r.RenderCommandFenceBundling"), GRenderCommandFenceBundling, TEXT(" 1: enabled (default);\n"), ECVF_Default)	(	TEXT("r.RenderCommandFenceBundling")	,
		GRenderCommandFenceBundling	,
		TEXT(" 1: enabled (default);\n")	,
		ECVF_Default
	)

◆ CVarRenderCommandPipeMode

FAutoConsoleVariable CVarRenderCommandPipeMode(TEXT("r.RenderCommandPipeMode"), 2, TEXT(" 2: Render commands are enqueued into a render command pipe for all declared pipes.;\n"), FConsoleVariableDelegate::CreateLambda([](IConsoleVariable *Variable) { UE::RenderCommandPipe::StopRecording(); GRenderCommandPipeMode=GetValidatedRenderCommandPipeMode(Variable->GetInt()); }))	(	TEXT("r.RenderCommandPipeMode")	,
		2	,
		TEXT(" 2: Render commands are enqueued into a render command pipe for all declared pipes.;\n")	,
		FConsoleVariableDelegate::CreateLambda([](IConsoleVariable *Variable) { UE::RenderCommandPipe::StopRecording(); GRenderCommandPipeMode=GetValidatedRenderCommandPipeMode(Variable->GetInt());})
	)

◆ GGameThreadTime

uint32 GGameThreadTime = 0

How many cycles the gamethread used (excluding idle time). It's set once per frame in FViewport::Draw.

◆ GGameThreadTimeCriticalPath

uint32 GGameThreadTimeCriticalPath = 0

How many cycles the gamethread used, including dependent wait time.

◆ GGameThreadWaitTime

uint32 GGameThreadWaitTime = 0

How much idle time on the game thread. It's set once per frame in FViewport::Draw.

◆ GIsRenderingThreadHealthy

volatile bool GIsRenderingThreadHealthy = true

Polled by the game thread to detect crashes in the rendering thread. If the rendering thread crashes, it sets this variable to false.

◆ GIsThreadedRendering

RENDERCORE_API bool GIsThreadedRendering = false

Whether the renderer is currently running in a separate thread. If this is false, then all rendering commands will be executed immediately instead of being enqueued in the rendering command buffer.

◆ GPendingUseThreadedRendering

RENDERCORE_API TOptional<bool> GPendingUseThreadedRendering

◆ GRenderCommandFenceBundling

bool GRenderCommandFenceBundling = true

◆ GRenderCommandPipeMode

ERenderCommandPipeMode GRenderCommandPipeMode = ERenderCommandPipeMode::None

◆ GRenderingThreadError

FString GRenderingThreadError

If the rendering thread has been terminated by an unhandled exception, this contains the error message.

◆ GRenderingThreadHeartbeat

FRunnableThread* GRenderingThreadHeartbeat = NULL

◆ GRenderingThreadMaxIdleTickFrequency

float GRenderingThreadMaxIdleTickFrequency = 40.f

Maximum rate the rendering thread will tick tickables when idle (in Hz)

◆ GRenderingThreadRunnableHeartbeat

FRunnable* GRenderingThreadRunnableHeartbeat = NULL

◆ GRenderThreadPollingOn

CORE_API bool GRenderThreadPollingOn

extern

RT Task Graph polling.

◆ GRenderThreadPollPeriodMs

CORE_API int32 GRenderThreadPollPeriodMs

extern

◆ GRenderThreadTime

uint32 GRenderThreadTime = 0

How many cycles the renderthread used (excluding idle time). It's set once per frame in FViewport::Draw.

◆ GRenderThreadTimeCriticalPath

uint32 GRenderThreadTimeCriticalPath = 0

How many cycles the renderthread used, including dependent wait time.

◆ GRenderThreadWaitTime

uint32 GRenderThreadWaitTime = 0

How many cycles of wait time renderthread used. It's set once per frame in FViewport::Draw.

◆ GRHIThread

FRHIThread* GRHIThread = nullptr

◆ GRHIThreadTime

uint32 GRHIThreadTime = 0

How many cycles the rhithread used (excluding idle time).

◆ GRunRenderingThreadHeartbeat

TAtomic<bool> GRunRenderingThreadHeartbeat

If the rendering thread is in its idle loop (which ticks rendering tickables

◆ GSuspendRenderingTickables

TAtomic<int32> GSuspendRenderingTickables

rendering tickables shouldn't be updated during a flush

◆ GSwapBufferTime

uint32 GSwapBufferTime = 0

How many cycles it took to swap buffers to present the frame.

◆ GTimeoutSuspendCount

std::atomic<int> GTimeoutSuspendCount

◆ GUseThreadedRendering

RENDERCORE_API bool GUseThreadedRendering = false

Whether the rendering thread should be created or not. Currently set by command line parameter and by the ToggleRenderingThread console command.

◆ OutstandingHeartbeats

FThreadSafeCounter OutstandingHeartbeats

Classes

Namespaces

Macros

Functions

Variables