System.Net.NameResolution.Tests.GetHostAddressesTest_Cancellation.DnsGetHostAddresses_PostCancelledToken_Throws failing in CI

[jakobbotsch]

Failure: https://dev.azure.com/dnceng-public/public/_build/results?buildId=94183&view=ms.vss-test-web.build-test-results-tab
Console log: https://helixre107v0xdeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-78879-merge-4f7487e318c446cc92/System.Net.NameResolution.Functional.Tests/3/console.b90e962b.log?helixlogtype=result

This has failed before: #69993. Back then it was disabled in jitstress (in #70089), but note that no stress modes are set in the scenario that failed.

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Issue Details

---

Failure: https://dev.azure.com/dnceng-public/public/_build/results?buildId=94183&view=ms.vss-test-web.build-test-results-tab
Console log: https://helixre107v0xdeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-78879-merge-4f7487e318c446cc92/System.Net.NameResolution.Functional.Tests/3/console.b90e962b.log?helixlogtype=result

This has failed before: #69993. Back then it was disabled in jitstress (in #70089), but note that no stress modes are set in the scenario that failed.

Author:	jakobbotsch
Assignees:	-
Labels:	area-System.Net
Milestone:	-

[jakobbotsch]

There's 2 failures in innerloop within the past 3 weeks: https://runfo.azurewebsites.net/search/timelines/?q=started%3A%7E21+definition%3Aruntime+message%3ADnsGetHostAddresses_PostCancelledToken_Throws

8 failures if you include libraries-jitstress, most often under tailcallstress: https://runfo.azurewebsites.net/search/timelines/?q=started%3A%7E21+message%3ADnsGetHostAddresses_PostCancelledToken_Throws

[jakobbotsch]

@rzikm @wfurt @antonfirsov If the flakiness cannot be fixed, can we add some kind of retry mechanism in the test, so that we only fail if e.g. 5/5 tries fail?

[rzikm]

There is global retry mechanism for all networking tests, the CI fails the test if it fails 3 times in a row.

[wfurt]

We should kick it to outerloop e.g. same as DnsGetHostEntry_PostCancelledToken_Throws.
Curiously the TestSettings.UncachedHost is used in multiple places so it may not work with negative caching.
retries may have similar problem.

[rzikm]

Triage: All tests touching external host should be moved to outerloop. We should have a look in 8.0 timeframe