[ci-scan] Hang: Abort_ConnectAndAbort_ThrowsWebSocketExceptionWithMessage times out on Windows #134806

Description

The non-SSL shared-handler loopback WebSocket abort test intermittently times out.

Reproduction Steps

Run the runtime CI pipeline's Windows x64 checked library tests; see the failing build and console log below. No deterministic local reproduction is known.

Expected behavior

Abort_ConnectAndAbort_ThrowsWebSocketExceptionWithMessage completes and validates the WebSocket exception.

Actual behavior

The client/server task group times out in LoopbackWebSocketServer.HttpRunner.RunAsync after about 102 seconds.

Regression?

Unknown; Build Analysis reports a 0.01% historical failure rate.

Known Workarounds

None confirmed.

Configuration

Windows x64, Release libraries tests, checked CoreCLR; useSsl: False, shared handler.

Other information

The source PR changes Wasm intrinsics, not WebSockets. Investigate client/server task completion in HttpRunner.RunAsync.

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1614059
Build error leg or test failing: net11.0-windows-Release-x64-coreclr_checked-Windows.Amd64.Open.rt-System.Net.WebSockets.Client.Tests.AbortTest_SharedHandler_Loopback.Abort_ConnectAndAbort_ThrowsWebSocketExceptionWithMessage
Pull request: #130050

Error Details

System.Net.WebSockets.Client.Tests.AbortTest_SharedHandler_Loopback.Abort_ConnectAndAbort_ThrowsWebSocketExceptionWithMessage(useSsl: False) [FAIL]
  System.TimeoutException : The operation has timed out.
  at System.Threading.Tasks.TaskTimeoutExtensions.WhenAllOrAnyFailed(Task[] tasks, Int32 millisecondsTimeout)
  at System.Net.WebSockets.Client.Tests.LoopbackWebSocketServer.HttpRunner.RunAsync(...)

Console log: https://helixr18s23ayyejvk1x8qcc.blob.core.windows.net/dotnet-runtime-refs-pull-130050-merge-26408109e459480cbe/System.Net.WebSockets.Client.Tests/1/console.adac8454.log?helixlogtype=result

Error Message

{
  "ErrorMessage": [
    "System.Net.WebSockets.Client.Tests.AbortTest_SharedHandler_Loopback.Abort_ConnectAndAbort_ThrowsWebSocketExceptionWithMessage(useSsl: False) [FAIL]",
    "System.TimeoutException : The operation has timed out."
  ],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1614059
Error message validated: [System.Net.WebSockets.Client.Tests.AbortTest_SharedHandler_Loopback.Abort_ConnectAndAbort_ThrowsWebSocketExceptionWithMessage(useSsl: False) [FAIL] System.TimeoutException : The operation has timed out.]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 9/28/2026 5:05:47 PM UTC

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Summary