x/tools/gopls/internal/filewatcher: TestFileWatcher/rename_directory_in_linux_&_windows failures

[gopherbot]

#!watchflakes
default <- pkg == "golang.org/x/tools/gopls/internal/filewatcher" && test == "TestFileWatcher/rename_directory_in_linux_&_windows"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestFileWatcher/rename_directory_in_linux_&_windows
==================
WARNING: DATA RACE
Write at 0x00c000242640 by goroutine 34:
  runtime.racewrite()
      <autogenerated>:1 +0x24
  golang.org/x/tools/gopls/internal/filewatcher.(*Watcher).Close()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher.go:421 +0x3e
  golang.org/x/tools/gopls/internal/filewatcher_test.TestFileWatcher.func12()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher_test.go:343 +0xdd1
...
Goroutine 37 (running) created at:
  golang.org/x/tools/gopls/internal/filewatcher.(*Watcher).handleEvent()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher.go:233 +0x533
  golang.org/x/tools/gopls/internal/filewatcher.(*Watcher).run()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher.go:128 +0x3f4
  golang.org/x/tools/gopls/internal/filewatcher.New.gowrap1()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher.go:74 +0x46
==================
    testing.go:1617: race detected during execution of test
--- FAIL: TestFileWatcher/rename_directory_in_linux_&_windows (0.65s)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "golang.org/x/tools/gopls/internal/filewatcher" && test == "TestFileWatcher/rename_directory_in_linux_&_windows"

2025-07-29 20:55 x_tools-gotip-windows-amd64-race tools@ef0f4a4c go@cc571dab x/tools/gopls/internal/filewatcher.TestFileWatcher/rename_directory_in_linux_&_windows (log)

=== RUN   TestFileWatcher/rename_directory_in_linux_&_windows
==================
WARNING: DATA RACE
Write at 0x00c000242640 by goroutine 34:
  runtime.racewrite()
      <autogenerated>:1 +0x24
  golang.org/x/tools/gopls/internal/filewatcher.(*Watcher).Close()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher.go:421 +0x3e
  golang.org/x/tools/gopls/internal/filewatcher_test.TestFileWatcher.func12()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher_test.go:343 +0xdd1
...
Goroutine 37 (running) created at:
  golang.org/x/tools/gopls/internal/filewatcher.(*Watcher).handleEvent()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher.go:233 +0x533
  golang.org/x/tools/gopls/internal/filewatcher.(*Watcher).run()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher.go:128 +0x3f4
  golang.org/x/tools/gopls/internal/filewatcher.New.gowrap1()
      C:/b/s/w/ir/x/w/targetrepo3412854684/gopls/internal/filewatcher/filewatcher.go:74 +0x46
==================
    testing.go:1617: race detected during execution of test
--- FAIL: TestFileWatcher/rename_directory_in_linux_&_windows (0.65s)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "golang.org/x/tools/gopls/internal/filewatcher" && test == "TestFileWatcher/rename_directory_in_linux_&_windows"

2025-11-07 18:25 x_tools-go1.25-windows-amd64-race tools@ca7a362d release-branch.go1.25@f2cd93aa x/tools/gopls/internal/filewatcher.TestFileWatcher/rename_directory_in_linux_&_windows (log)

=== RUN   TestFileWatcher/rename_directory_in_linux_&_windows
    filewatcher_test.go:278: found 2 matching events slice
        want sequences:
        URI: foo type: Deleted
        URI: baz type: Created
        URI: baz/bar.go type: Created
        
        all got:
        URI: C:\b\s\w\ir\x\t\TestFileWatcherrename_directory_in_linux_&_windows3150694137\001\foo type: Deleted
        URI: C:\b\s\w\ir\x\t\TestFileWatcherrename_directory_in_linux_&_windows3150694137\001\baz type: Created
--- FAIL: TestFileWatcher/rename_directory_in_linux_&_windows (30.94s)

— watchflakes

[h9jiang]

Interesting. With a little bit investigation, I think the problem is coming from filepath.WalkDir() in windows.

filepath.WalkDir will try to open a dir and walk through all the entries in that dir. If the filepath.WalkDir failed to open the dir, func(path, info, err) the last input parameter will be non-nil.

And there is no way of retrying this.

When the test failed in windows, open dir failed with error

path/to/baz: The process cannot access the file because it is being used by another process.

So maybe we should not use filepath.WalkDir, we need a function that try to open the dir at least 3 times before claim it's failing.

I will experiment and send out a CL for fix.

[h9jiang]

In this case, the filewatcher and it's test are racing with each other. But this is intended.

The test is trying to rename a dir meaning, create a new dir with files and sub dirs. And the file watcher is trying to watch for that dir. After quick discussion with Alan and Rob, we will use robustio.IsEphemeralError to determine whether a read error is retriable or not.

If so, retry a few times.

If not, call err handler with the captured error.

[gopherbot]

Change https://go.dev/cl/719320 mentions this issue: gopls/internal/filewatcher: add retry in dir watching