File watcher maxes CPU when folder contains symlink loop

[drkvogel]

Following instructions from https://stackoverflow.com/a/48214059/535071, I profiled a rogue bootstrap-fork --type=watcherService and recorded a CPU profile: CPU-20210331T105942.zip

The top 8 rows by CPU time:

Self Time   Total Time  File
9,064.72ms  9,064.72ms  _addPathCloser /home/kvogel/.vscode-server/bin/2b9aebd5354a3629c3aba0a5f5df49f43d6689f8/node_modules/chokidar/index.js:922
591.25ms    591.25ms    (garbage collector)
92.40ms     92.40ms     (program)
73.56ms     73.56ms     lstat
27.94ms     35.31ms     resolve path.js:972
19.97ms     69.24ms     LOOP fs.js:1723
19.86ms     19.86ms     FSReqCallback
17.34ms     17.34ms     stat

chokidar - npm
paulmillr/chokidar: Minimal and efficient cross-platform file watching library

Originally posted by @drkvogel in #3126 (comment)

[drkvogel]

Turns out I have symlink directory loop in one of the folders I was connecting to with "Remote - WSL":

❯ file ../pz/legacy/sites/1/htdocs/shared/pz
../pz/legacy/sites/1/htdocs/shared/pz: symbolic link to ../../../

and when I click "Reconnect" after getting the "Cannot Reconnect" dialog after resuming from hibernation, I get several bootstrap-fork --type=watcherService processes which max out the CPU and that I have to kill off.

(Full path: /home/user/.vscode-server/bin/2b9aebd5354a3629c3aba0a5f5df49f43d6689f8/node /home/user/.vscode-server/bin/2b9aebd5354a3629c3aba0a5f5df49f43d6689f8/out/bootstrap-fork --type=watcherService)

I attached a debugger to one of these processes, and in devtools, file: VM path.js, Local variables, found something like:

path: /home/user/projects/myproject/pz/legacy/sites/1/htdocs/shared/includes/sites/shared/includes/sites/shared/includes/sites/shared/includes/sites/shared/includes/sites/shared/includes/sites/shared/includes/sites/shared/includes/sites/shared/includes/sites/shared/includes/js/colorbox/

which would seem to indicate that a symlink directory loop is being followed infinitely. Certainly, this doesn't happen on any other folder/repo/project.

[drkvogel]

Also, shouldn't files that are excluded from search be excluded by the file watcher?
In my project, Search, "files to exclude" included ./pz which contained the offending symlink loop.

[aeschli]

@bpasero FYI, also see question #4818 (comment)

[bpasero]

If one of our watchers fails over circular symbolic links, I suggest to report this as issue to the watcher in use. I am not sure which watcher we end up using in remote setups.

If a watcher fails to exclude a directory, even though indicated by settings, please file an issue in https://github.com/Microsoft/vscode/ with clear steps how to reproduce. Note that if NSFW watcher is used, we do not support excludes (see microsoft/vscode#40898)