CancelPendingFlushDuringBackpressureThrows test fails on arm32

[EgorBo]

  Starting:    System.Text.Json.Tests (parallel test collections = on [2 threads], stop on fail = off)
    System.Text.Json.Serialization.Tests.PipeTests.CancelPendingFlushDuringBackpressureThrows [FAIL]
      Assert.Equal() Failure: Values differ
      Expected: 11
      Actual:   13
      Stack Trace:
           at System.Text.Json.Serialization.Tests.PipeTests.CancelPendingFlushDuringBackpressureThrows()
        --- End of stack trace from previous location ---

Example: https://dev.azure.com/dnceng-public/public/_build/results?buildId=678396&view=ms.vss-test-web.build-test-results-tab

Build Information

Build:
Build error leg or test failing:

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "CancelPendingFlushDuringBackpressureThrows [FAIL]",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=678396
Error message validated: [CancelPendingFlushDuringBackpressureThrows [FAIL]]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 5/17/2024 2:38:23 PM UTC

Report

Build	Definition	Test	Pull Request
681018	dotnet/runtime	System.Text.Json.Serialization.Tests.PipeTests.CancelPendingFlushDuringBackpressureThrows	#102188
678396	dotnet/runtime	System.Text.Json.Serialization.Tests.PipeTests.CancelPendingFlushDuringBackpressureThrows

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
1	2	2

[EgorBo]

Looks like this test was introduced recently in #101461

cc @BrennanConroy
if that helps, in this outerloop pipeline JIT (and everything else) is quite slow so if a test relies on some timings it might fail

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-text-json, @gregsdennis
See info in area-owners.md if you want to be subscribed.

[v-wenyuxu]

Failed in: runtime-coreclr libraries-jitstress2-jitstressregs 20240518.1

Failed tests:

net9.0-linux-Release-arm-jitstress2_jitstressregs0x80-(Ubuntu.1804.Arm32.Open)Ubuntu.2004.Armarch.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-18.04-helix-arm32v7
    - System.Text.Json.Serialization.Tests.PipeTests.CancelPendingFlushDuringBackpressureThrows

Error message:

 Assert.Equal() Failure: Values differ
Expected: 11
Actual:   13

Stack trace:

   at System.Text.Json.Serialization.Tests.PipeTests.CancelPendingFlushDuringBackpressureThrows()
--- End of stack trace from previous location ---