[HTTP] Fix test race with semaphore.

[ManickaP]

Fixes #39056

[ManickaP]

/azp list

[azure-pipelines]

CI/CD Pipelines for this repository:

• runtime-coreclr outerloop
• runtime-coreclr jitstress
• runtime-coreclr jitstressregs
• runtime-coreclr jitstress2-jitstressregs
• runtime-coreclr gcstress0x3-gcstress0xc
• runtime-coreclr gcstress-extra
• runtime-coreclr r2r-extra
• runtime-coreclr jitstress-isas-x86
• runtime-coreclr jitstress-isas-arm
• runtime-coreclr jitstressregs-x86
• runtime-coreclr libraries-jitstressregs
• runtime-coreclr libraries-jitstress2-jitstressregs
• runtime-coreclr r2r
• runtime-coreclr runincontext
• runtime-coreclr crossgen2
• runtime-libraries-coreclr outerloop
• runtime-libraries-coreclr outerloop-windows
• runtime-libraries-coreclr outerloop-linux
• runtime-libraries-coreclr outerloop-osx
• runtime
• runtime-libraries enterprise-linux
• runtime-libraries stress-http
• runtime-libraries stress-ssl
• runtime-dev-innerloop
• runtime-coreclr crossgen2 outerloop
• coreclr-release-outerloop-nightly
• runtime-coreclr crossgen2-composite
• runtime-jit-experimental
• runtime-coreclr libraries-jitstress
• dotnet-linker-tests
• runtime-coreclr ilasm
• runtime-coreclr crossgen2-composite gcstress
• runtime-coreclr pgo
• runtime-coreclr libraries-pgo
• Antigen
• runtime-community
• Fuzzlyn
• runtime-coreclr superpmi-replay
• runtime-wasm
• runtime-coreclr superpmi-diffs
• runtime-coreclr superpmi-asmdiffs-checked-release
• runtime-extra-platforms
• jit-cfg
• runtime-wasm-perf
• runtime-llvm
• runtime-coreclr jitstress-random
• runtime-coreclr libraries-jitstress-random
• runtime-wasm-non-libtests
• runtime-android
• runtime-androidemulator
• runtime-ioslike
• runtime-ioslikesimulator
• runtime-linuxbionic
• runtime-maccatalyst
• runtime-coreclr pgostress
• runtime-coreclr jitstress-isas-avx512
• runtime-libraries-mono outerloop
• runtime-sanitized
• runtime-wasm-dbgtests
• runtime-wasm-optional
• runtime-nativeaot-outerloop
• runtime-coreclr superpmi-collect-test
• runtime-diagnostics
• runtime-interpreter
• runtime-report-green
• runtime-coreclr hardware-intrinsics
• runtime-libraries-interpreter
• runtime-vmr-validation

[dotnet-policy-service]

Tagging subscribers to this area: @karelz, @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

[ManickaP]

/azp run runtime-libraries-coreclr outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull request overview

This PR fixes a race condition in the Send_TimeoutRequestContent_Throws test where the server connection could close before the client properly timed out, causing the test to fail intermittently with an HttpRequestException instead of the expected TaskCanceledException with TimeoutException inner exception.

Changes:

• Removed the [ActiveIssue] attribute that was tracking the flaky test
• Added semaphore-based synchronization between client and server to ensure the server stays alive until the client completes its assertions

[Copilot]

The semaphore wait should include a timeout and assertion to prevent the test from hanging if the client-side assertions fail before releasing the semaphore. The established pattern in this test file is to use Assert.True(await semaphore.WaitAsync(5000), "semaphore timed out") to ensure the test fails fast with a clear message rather than hanging indefinitely. See lines 484, 647, and 717 for examples of this pattern.

Suggested change

	await semaphore.WaitAsync();
	Assert.True(await semaphore.WaitAsync(5000), "semaphore timed out");

[MihaZupan]

Thanks.

I wonder if we should make this an option on the factory eventually, e.g. DelayServerShutdownUntilClientCompletion. Not sure it's feasible/worth it to wire though though.
We have such SemaphoreSlim/TaskCompletionSource in a bunch of places.