[browser/WASM + .NET9] why is the garbage collector still not doing its job?

[DierkDroth]

Description

I had an open issue here which was closed as being fixed. However, it turns out that it's not fixed at all with .NET 9.

This made me update the repo to latest dependencies:
Minimal.zip

Scenario:

• basically this is a small Platform UNO app, which can be compiled for WindowsAppSDK or Platform UNO WASM (which uses Blazor WASM)
• WASM: by simply adding and removing elements to/from the visual tree the GC could be chased easily into an OutOfMemory exception
• FAIK there is no memory leak in the minimal custom code, so it must be a problem with the WASM runtime/GC

I confirmed by working with @jeromelaban (CTO, Platform UNO) that this by no means is a Platform UNO issue but clearly a .NET WASM issue. He pointed out that adding GC.GetTotalMemory(true); to the code would workaround the issue. Please review the minimal code and the comments which I added.

WASM: Why is the GC not releasing memory for objects which are no longer in use? Why would I have to explicitly call GC.GetTotalMemory(true); to make sure the GC does its job?

Reproduction Steps

see above

Expected behavior

see above

Actual behavior

see above

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

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[huoyaoyuan]

The fix #108512 was not backported to 9.0.

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[DierkDroth]

@huoyaoyuan thanks for your feedback. So it only would be available with .NET10, correct?

[huoyaoyuan]

You can raise a request for backport here. If approved, it will be available in future patches of 9.0.

[DierkDroth]

Thanks for clarification @huoyaoyuan

[pavelsavara]

There is known workaround and the backport is not planned.

[DierkDroth]

@pavelsavara to clarify:

• what would be the workaround you're referring to?
• which .NET version would hold the fix? .NET 9? .NET 10?