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[UE4] Memory leak problem

Lijin

Hello, I found that there's a memory leak caused by SpineSkeletonRendererComponent. The memory of FPhysXAllocator keeps increasing. And by adding breakpoint I found it's created continuously by SpineSkeletonRendererComponent.(As the images attached here)
My actor blueprint is set according to UE4 runtime tutorial (just attached a SpineSkeletonAnimationComponent and a SpineSkeletonRendererComponent to root, set my atlas and skeletondata, and called AnimationComponent->SetAnimation in beginplay). My Collision Presets is set to BlockAll by default. Then I just put the actor in my map. My UnrealEngine version is 4.27.2
I tried to change my atlas and skeletondata to the spineboy assets provided by UE4 runtime tutorial, and found it has a memory leak as well.
I also tried to change physics to NoCollision, and found there is no memory leak any more.

Has anyone encountered with same problem? I doubt it's a bug of ue4 spine runtime plugin. If so, how can I fix it without having to change my collision presets? Or am I missing any settings? Thanks.

Lijin

Mario

It's an issue in UE4 we've been trying to fix for over 2 years. Spine needs to update collision meshes of ProceduralMssh each frame. It seems UE4 doesn't like that at all. Worse, in the editorz it also creates gigabytes of data on disk.

I fear we'll have to remove collision mesh support from spine-ue4 entirely. Users will have to create custom collision shapes and attach them to their actor themselves.

PatrolCat

Mario I also encountered this memory leak issue in our project, and it's a serious problem. I tested it using UE4's performance analysis tool and found that even when doing nothing, Spine would have a memory leak of 2MB per second, which is similar to the memory leak from the physics module mentioned by the questioner. I have reviewed your rendering code and it seems obvious to me that the way to fix it is to avoid creating the Mesh every frame, as it's unnecessary. You only need to recreate the Mesh when it's updated; otherwise, you just need to Update it. I tried modifying the rendering logic of the SpineRenderer, and the memory leak disappeared. I wonder if you could consider making this change officially, as it's a very serious issue.

Lijin

Okay, got it. Thanks for your reply!

Edit:
To make sure, if I don't need any collision support, just want to fix the memory leak problem, then changing to NoCollision is the solution for now, is it? Are there any better solutions?

Mario

Yes, until i remove the physics code entirely from spine-ue4, setting it to NoCollision should do the trick.

PatrolCat

I have reviewed your rendering code and it seems obvious to me that the way to fix it is to avoid creating the Mesh every frame, as it's unnecessary. You only need to recreate the Mesh when it's updated; otherwise, you just need to Update it. I tried modifying the rendering logic of the SpineRenderer, and the memory leak disappeared.
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I wonder if you could consider making this change officially, as it's a very serious issue.

Lijin

Thanks.

PatrolCat

I found that I can't send pictures about memory testing in the post content, but it doesn't matter. I will roughly describe the modifications in words: 1. In the SpineSkeletonRendererComponent.cpp file, modify CreateMeshSection() to UpdateMeshSection() in the Flush() method, of course some judgments need to be made to determine whether to update this MeshSection; 2. At the same time, comment out the original ClearAllMeshSections() statement in the USpineSkeletonRendererComponent::UpdateMesh(Skeleton* Skeleton) function.

Mario

There is no way to determine if the mesh needs updating or not. Your point 1. of "of course some judgements need to be made to determine whether to update this MeshSection" is exactly the issue. You can possibly fix this for a handful of assets in your specific game, but there is no way to fix this for every possible project out their generally in the runtime.

You are also not fixing the memory leak. You are just making it take longer to become apparent.

This needs to be fixed on Epic's side.

PatrolCat

Mario Of course I'm not very familiar with your internal Spine code, but at least with some simple judgments, we can complete the determination of how to update MeshSection, which can handle simple scenarios and reduce 99% of memory leaks. This is at least better than doing nothing. You should know that a memory leak of 0.2MB per second can make this plugin very difficult to use on mobile devices.

Mario

There are no "simple judgements" we can apply to our general spine-ue runtime. As I explained, you can do that on your end, by modifying the spine-ue sources with the full knowledge of your project. We do not have that knowledge, neither for your project, nor for anyone elses projects. We therefore can not apply such "simple judgements". They don't exist. I'm happy to integrate anything that's general enough that you came up with.

And as I explained in my last post as well: you can not get rid of the memory leak. You are simply post-poning the time of crash. The leak is still there. It is a UE problem, not something we can fix on our end.