Skip to content

perf(manager): apply the render snapshot outside its lock #4

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
finger563 merged 1 commit into from
Oct 10, 2026
Merged

perf(manager): apply the render snapshot outside its lock #4

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
43 changes: 27 additions & 16 deletions Source/URLab/Private/MuJoCo/Core/AMjManager.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -760,26 +760,37 @@ void AAMjManager::ApplyLatestRenderState()
const TArray<AMjArticulation*>& Arts = PhysicsEngine->GetAllArticulations();
const TArray<UMjQuickConvertComponent*> Quicks = PhysicsEngine->GetAllQuickComponents();

PhysicsEngine->WithRenderState([&](const FMjRenderSnapshot& Snap) {
for (AMjArticulation* Art : Arts)
// Copy the frame out and apply it after releasing the snapshot lock. The
// stepping thread takes that lock to publish, and applying a frame moves
// every body and geom component in the scene -- milliseconds on a large
// model, tens of them on a slow frame -- while copying it is microseconds.
// Applying under the lock held the stepper behind the game thread for
// most of every frame: a 140-body, 485-geom robot stepped at about a
// quarter of real time with MuJoCo itself idle 95% of the time.
//
// Game thread only, and used start to finish within this call, so one
// buffer serves every call and keeps its allocations between frames.
static FMjRenderSnapshot Applied;
PhysicsEngine->WithRenderState([](const FMjRenderSnapshot& Snap) { Applied = Snap; });

for (AMjArticulation* Art : Arts)
{
if (Art)
{
if (Art)
{
Art->ApplyRenderState(Snap);
}
Art->ApplyRenderState(Applied);
}
for (UMjQuickConvertComponent* Quick : Quicks)
}
for (UMjQuickConvertComponent* Quick : Quicks)
{
if (Quick)
{
if (Quick)
{
Quick->ApplyRenderState(Snap);
}
Quick->ApplyRenderState(Applied);
}
// Record which post-step state the actors now reflect so cameras can
// tag their readbacks with it (frame_id association for the bridge).
LastAppliedRenderFrameId.store(Snap.FrameId, std::memory_order_release);
LastAppliedRenderSimTime.store(Snap.SimTime, std::memory_order_release);
});
}
// Record which post-step state the actors now reflect so cameras can
// tag their readbacks with it (frame_id association for the bridge).
LastAppliedRenderFrameId.store(Applied.FrameId, std::memory_order_release);
LastAppliedRenderSimTime.store(Applied.SimTime, std::memory_order_release);
}

AAMjManager* AAMjManager::GetManager()
Expand Down
Loading