We’re having an issue where the game hitches every 30-60s, the attached Unreal Insight screenshots show that the hitches are caused by UpdateGPUScene_Primitives taking much longer than usual.
Is there any advice on what might be causing that or on a way to track down the culprit?
Hi,
thanks for reaching out. This issue seems similar to the one reported [Content removed] (that issue has been fixed with this commit). It’s possible that a large amount of primitives are being invalidated/marked as dirty which causes large batches of primitives to be uploaded to the GPU with FGPUScene::UploadGeneral(), which uploads primitives and instances in parallel.
You can try placing a breakpoint at the top of FGPUScene::UploadGeneral() and inspect the call stack when it breaks to narrow down the cause.
A few more questions: Do these hitches occur when the camera is moving or also when it remains static? Can you please check if your project has the fix from the commit I linked to is already included in your project? Lastly, is it possible to try your project in 5.5 and check if the same hitches still occur (it’s possible that there’s already a fix)?
Please let me know how that goes.
Best,
Sam
Hi Sam,
Thank you for the prompt response! Our project is currently on UE 5.4.4 so the fix you linked is indeed included. Apparently something else causes the issue for us. According to our QA the hitches happen for both moving and static camera. Upgrading to 5.5 isn’t really possible at the moment as the engine upgrade is scheduled post our early access release considering related risks and efforts required. I will try to debug it based on your advice and will report back if I find anything.
Best regards,
Roman
Thank you for following up. I’m definitely interested to find out more about the root cause of these hitches as it might help others and also potentially improve the engine.
Best regards,
Sam