[ci-scan] Test failure: PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated ("Chan [Content truncated due to length]

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Known Build Error

{
  "ErrorMessage": [
    "CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated",
    "Change token did not fire within 30 seconds."
  ],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Summary

Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated fails with a TimeoutException — the file-change token does not fire within 30 seconds after the watched root directory is deleted and recreated.

[FAIL] Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated(useActivePolling: False)
System.TimeoutException : Change token did not fire within 30 seconds.

Where it fails

• Pipeline: runtime-coreclr libraries-pgo (definition 145, optional rolling)
• Leg: net11.0-linux-Release-x64-defaultpgo
• Queue: AzureLinux.3.Amd64.Open

Occurrences

• First build it occurred: 1500203 (2026-07-09)
• Source build for this filing: 1505119 (finished 2026-07-12T18:52Z)
• Follow-up build confirming persistence: 1508411 (signature still present)

The failure is intermittent within the scanned window (present in builds 1500203, 1505119, 1508411; absent in some intervening builds), consistent with a timing-sensitive file-watcher timeout that surfaces under PGO instrumentation.

Notes

Detected by the CI outer-loop failure scanner. Area triage is delegated to the issue labeler. This is a detection-only KBE; mitigation is handled separately.

Generated by CI Outer-Loop Failure Scanner · 546.2 AIC · ⊞ 19.5K · ◷

Report

Build	Repository	Test	Pull Request
1519105	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130512
1519062	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131087
1519047	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130838
1518923	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130556
1518843	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131117
1518833	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#129915
1518811	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131113
1518566	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130505
1518401	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#129543
1518105	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131089
1517570	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131071
1517423	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130958
1516942	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131019
1516689	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130761
1516496	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131019
1516459	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131017
1516246	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated
1516215	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#131015
1515512	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130985
1515025	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130790
1514750	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130966
1514507	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130888
1514303	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130958
1514355	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated
1514182	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130949
1514133	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130946
1513689	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130899
1513510	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated
1509456	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated	#130062

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
0	28	29

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

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Workflow artifact: ci-fix
Artifact kind: handoff
Linked KBE: #130940

Note

AI/Copilot-generated root-cause hand-off (ci-failure-fix). No automated code change was produced: the file-watcher already implements the obvious gap-closing paths, and the residual failure is an inotify event-delivery race that has no small, validatable fix and needs a maintainer design decision (never a test-disable). Looping in owners to fix forward.

Root cause (read-only analysis)

PhysicalFilesWatcherTests.CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated(useActivePolling: False) intermittently times out (Change token did not fire within 30 seconds) on the libraries-pgo leg (net11.0-linux-Release-x64-defaultpgo, AzureLinux.3.Amd64.Open).

The non-polling flow the test exercises (PhysicalFilesWatcherTests.cs:615-649):

1. Watch file.txt, then Directory.Delete(root) → the real FileSystemWatcher fires OnError → CancelAll fires the initial token and TryDisableFileSystemWatcher runs.
2. Re-watch file.txt while root is missing → TryEnableFileSystemWatcher sees !Directory.Exists(_root) and calls EnsureRootCreationWatcher, which spins up a PendingCreationWatcher (PCW) watching root's parent for the root directory's (re)creation (PhysicalFilesWatcher.cs:559-639, 662-706).
3. Directory.CreateDirectory(root) must be observed by the PCW's inotify watch → its OnCreated cancels the CTS → the registered callback re-invokes TryEnableFileSystemWatcher, which re-enables the main FSW and calls ReportExistingWatchedEntries() to cover files created in the enable gap (PhysicalFilesWatcher.cs:484-516, 640-653).
4. File.WriteAllText(root/file.txt) is then detected either by the live main FSW or by the ReportExistingWatchedEntries re-scan → token fires.

The gap-closing mechanisms are already present: ReportExistingWatchedEntries (step 3) re-scans for entries created before the FSW became active, and SetupWatcherNoLock has post-start race checks (PhysicalFilesWatcher.cs:918-938). Those cover the enable-then-file-created window.

The residual flake is the dependency in step 3 on the PCW's inotify watch actually delivering the parent-directory Created event for the recreated root. If that single event is dropped or delayed under PGO instrumentation load, TryEnableFileSystemWatcher is never re-invoked, the main FSW is never re-enabled, ReportExistingWatchedEntries never runs, and the token never fires within 30s. This is inherent inotify event-delivery unreliability under load, not a discrete logic bug — so there is no small, in-bounds, validatable code change I can make. A real fix (e.g. a bounded polling fallback for the root-recreation wait when useActivePolling is false, or otherwise not relying on a single un-acked inotify event) is a design decision for the area owners, and I could not reproduce/validate it in this environment.

Muting the test (e.g. [ActiveIssue]/platform skip) is explicitly not an option for this workflow.

Evidence

• Failing builds: 1515512, 1508411; first occurrence build 1500203 (2026-07-09). 7-day hit count 10, intermittent (absent in some intervening builds) — consistent with a timing-sensitive inotify race surfaced under PGO instrumentation.
• Test: src/libraries/Microsoft.Extensions.FileProviders.Physical/tests/PhysicalFilesWatcherTests.cs:615.
• Watcher: src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFilesWatcher.cs — root-recreation path (EnsureRootCreationWatcher 662-706, PendingCreationWatcher 808+), gap cover (ReportExistingWatchedEntries 484-516, invoked 640-653).

Suggested reviewers / area contacts

• Area owners (area-Extensions-FileSystem): @anicka-net, @dotnet/area-extensions-filesystem (consultants: @jozkee, @adamsitnik).

Generated by CI Outer-Loop Failure Fixer · 408.1 AIC · ⊞ 18.2K · ◷