F# sdk_scenarios hitting OOM during x86 build tests

[LoopedBard3]

F# tests that are part of sdk_scenarios are hitting OOM exceptions during their testing (during build). I plan on disabling the tests for x86 for now so this will track fixing and reenabling it. The F# scenario also seems pretty out of date so may see if it needs to be updated as well.

Error:

(.venv) <dir>\e>python test.py sdk build_no_change --scenario-name "F# Compiler Service Build(No Change)" --upload-to-perflab-container 
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Initializing logger 2025-09-23 12:24:03.115932
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$ <basedir>\p\startup\Startup.exe --app-exe dotnet --metric-type ProcessTime --trace-name "F# Compiler Service Build(No Change)_startup" --gui-app false --process-will-exit true --iterations 5 --timeout 600 --warmup true --working-dir app --report-json-path traces\perf-lab-report.json --trace-directory traces --scenario-name "F# Compiler Service Build(No Change)" --app-args build --environment-variables DOTNET_MULTILEVEL_LOOKUP=0
Running dotnet (args: "build")
Working Directory: app
Iteration set up:  (args: )
Iteration clean up:  (args: )
=============== Warm up ================
***Test***
Added environment variable: DOTNET_MULTILEVEL_LOOKUP=0
  Determining projects to restore...
  Restored <dir>\e\app\FSharp.Compiler.Service.fsproj (in 685 ms).
<basedir>\p\dotnet\sdk\10.0.100-rc.2.25468.104\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.RuntimeIdentifierInference.targets(351,5): message NETSDK1057: You are using a preview version of .NET. See: https://aka.ms/dotnet-support-policy [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Utilities\sformat.fs(1632,9): warning FS1182: The value 'output_any' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Utilities\sformat.fs(1638,9): warning FS1182: The value 'any_to_string' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Utilities\sr.fs(32,9): warning FS1182: The value 'mkFunTy' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Utilities\illib.fs(922,9): warning FS1182: The value 'canceled' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Utilities\FileSystem.fs(38,9): warning FS1182: The value 'sub' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Utilities\lib.fs(601,16): warning FS1182: The value 'iter' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Utilities\ImmutableArray.fs(77,9): warning FS1182: The value 'map2' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Utilities\ImmutableArray.fs(92,9): warning FS1182: The value 'mapi2' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Facilities\CompilerLocation.fs(54,9): warning FS1182: The value 'maxDataLength' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\AbstractIL\il.fs(4627,7): warning FS3548: Pattern discard is not allowed for union case that takes no data. [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\AbstractIL\il.fs(32,5): warning FS1182: The value 'int_order' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\AbstractIL\il.fs(94,5): warning FS1182: The value 'splitNamespaceMemoized' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\AbstractIL\il.fs(147,5): warning FS1182: The value 'unsplitTypeName' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\AbstractIL\il.fs(429,5): warning FS1182: The value 'isMscorlib' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\AbstractIL\il.fs(3237,5): warning FS1182: The value 'filterILMethodDefs' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\AbstractIL\il.fs(3455,5): warning FS1182: The value 'tname_CompilerGeneratedAttribute' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\AbstractIL\il.fs(3458,5): warning FS1182: The value 'tname_DebuggableAttribute' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
....... (bunch more warnings)
<dir>\e\app\Service\ServiceLexing.fs(30,9): warning FS1182: The value 'HASH_IDENT' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Service\ServiceInterfaceStubGenerator.fs(526,19): warning FS1182: The value '(|EventFunctionType|_|)' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Service\ServiceStructure.fs(67,9): warning FS1182: The value 'rangeOfSynPatsElse' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Interactive\fsi.fs(282,11): warning FS3548: Pattern discard is not allowed for union case that takes no data. [<dir>\e\app\FSharp.Compiler.Service.fsproj]
<dir>\e\app\Legacy\LegacyMSBuildReferenceResolver.fs(30,18): warning FS1182: The value 'ReplaceVariablesForLegacyFxOnWindows' is unused [<dir>\e\app\FSharp.Compiler.Service.fsproj]
error FS0193 : internal error : Exception of type 'System.OutOfMemoryException' was thrown. [<dir>\e\app\FSharp.Compiler.Service.fsproj]
    219 Warning(s)
    1 Error(s)
Time Elapsed 00:00:46.68


Process 24000 failed to run. Result: ExitedWithError
Process exited with status 4294967295
Run failure registered

[LoopedBard3]

@0101 (Presuming you still do stuff with FSharp) With all these warnings, I wonder if it may just be necessary to update these tests to use the latest or release/8.0 version of the FSharp code. It seems that the current scenario of building the FSharp Compiler Service may not be an easy update as my quick src update attempt failed to build due to references outside of the Compiler Service needing to be included.

Are these tests still used/useful?

[0101]

@LoopedBard3 unfortunately I don't.

We need to ask @T-Gro

[T-Gro]

Can you please correlate that to an SDK version bump or anything in that direction?
I would first suspect this might be a real product (= compiler) regression when it comes to memory consumption.

TLDR: The tests are useful, especially when they fail and discover a product issue 👍

[LoopedBard3]

Seems we started running the test on the failing hardware after whatever is causing this as I am not finding any results for the specific setup in our testing data. We started running on the specific hardware ~3 months ago. Also, we are seeing this with the net10, net9, and net8 sdks, so it maybe is not something that was introduced. We have on machine access so we can run some tests and gather traces, is there a specific trace type/setup that you think would be good to start with?

[T-Gro]

The compiler is doing a lot of work to compile itself, I think the best would be to use the tracing env vars https://github.com/dotnet/runtime/blob/main/docs/design/features/host-tracing.md#trace-routing and locate the error.

We likely do not have any compiler contributor on a 32bit system, so this might have been in existence without spotting for a while.
But if we can locate the right place, we could on a 32bit system opt-in segmented arrays for selected data structures to avoid allocations of a single massive array - I assume that has been the case for the OOMException here.