Intermittent crash when GeometryCollectionComponent is registered after level has been streamed in

Development Asset Creation
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1

Hi, we are experiencing a crash that seems to happen randomly when streaming in a levels that contains geometry collections.

Has this issue been seen before or would you have any suggestions on how to approach this issue?

Additional info:

The levels are injected into streaming grid during runtime using UWorldPartitionRuntimeHashSet::RegisterWorldAssetStreaming.

Issues does not seem to happen on the server which has streaming disabled.

Not sure if it is relevant we have async physics and fast geo enabled.

So far only managed to reproduce in the packaged build only, but it could be just editor being slower and it seems like it’s some timing related issue.

PendingSpatialOperations_External.PendingData was invalid, but the rest of the variables seem to be sane.

-		PendingSpatialOperations_External	Ptr=0x000002418a450fc0 {PendingData=Invalid ParticleToPendingData={Entries=Num=55296, Max=63488 } }	TUniquePtr<Chaos::FPendingSpatialDataQueue,TDefaultDelete<Chaos::FPendingSpatialDataQueue>>
		PendingData	Invalid	TArray<Chaos::FPendingSpatialData,TSizedDefaultAllocator<32>>
-		ParticleToPendingData	{Entries=Num=55296, Max=63488 }	Chaos::TArrayAsMap<Chaos::FUniqueIdx,int>
-		Entries	Num=55296, Max=63488	TArray<Chaos::TArrayAsMap<Chaos::FUniqueIdx,int>::FEntry,TSizedDefaultAllocator<32>>
+		[0]	{Value=1608340352 bSet=false }	TArray<Chaos::TArrayAsMap<Chaos::FUniqueIdx,int>::FEntry,TSizedDefaultAllocator<32>>::ElementType
+		[1]	{Value=1608340352 bSet=false }	TArray<Chaos::TArrayAsMap<Chaos::FUniqueIdx,int>::FEntry,TSizedDefaultAllocator<32>>::ElementType
+		[2]	{Value=1696446848 bSet=false }	TArray<Chaos::TArrayAsMap<Chaos::FUniqueIdx,int>::FEntry,TSizedDefaultAllocator<32>>::ElementType

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2

Steps to Reproduce
Repeatedly stream in and stream out a level that contains geometry collections.

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3

Hello [mention removed]​

I’ve tested your repro project against the latest UE5.8 Perforce version, and the crash is still being reproduced.

I’ve also searched for a mention of such an issue both here and on the issue tracker website, but found nothing, so I’ve made a JIRA report at: Unreal Engine Issues and Bug Tracker (UE\-358459) (please note that it can take some time to be made publicly accessible).

We don’t provide updates on EPS, but if you would like to track the resolution, check the link for the status.

I was not able to find a workaround, but during my tests, I noticed that disabling Tick Physics Async mitigated the issue. I also read about the console command “p.Chaos.EnableAsyncInitBody”, which is experimental, but setting the flag to false crashed the repro project immediately.

These are all experimental features, and their interaction is still rather fragile.

For now, I recommend avoiding the combination of Async Physics and level streaming.

Let me know if this is helpful.

All the best,

[mention removed]​

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Thank you for the help, the async physics was enables as per recommendation here:

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However it seems to work without it, so we shall run with that for now.

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Hello [mention removed]​

Thank you for reaching out.

I’ve just been assigned your case and will try to replicate it.

I’ll let you know how it goes.

All the best,

[mention removed]​

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6

Hello [mention removed]​

I’ve been trying to reproduce the described behavior, but haven’t been successful so far.

Would it be possible to provide a minimal project that reproduces this issue?

Further details I can follow to recreate the project locally would work just as well.

I hope to hear from you soon.

All the best,

[mention removed]​

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Hi Rafael, after some time of tinkering, we managed to make a very consistent repro in minimal project that I am attaching. Part was setting up the level loading/unloading, but also parts of our project settings ware required to trigger this crash.

To reproduce this issue load this project (stock 5.6.1), package the project using windows development configuration and run the packaged executable.

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Hello [mention removed]​

Thank you for taking the time to create this repro project.

I was able to reproduce the crash.

I’ll research some more and get back to you.

All the best,

[mention removed]​

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9

Hello [mention removed]​

Thank you for marking my answer as Best Answer!

I’ll close the case.

If you have further issues, you can reply or open a new case and tag this one for historical context.

All the best,

[mention removed]​

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