Workspace enumeration follows symlinks out of the workspace: wine prefix dosdevices/z: -> / pins a CPU core at 100% and floods the log #5620

Type: Performance Issue

Summary

The PowerShell language server (PSES) recursively enumerates the whole workspace on startup looking for .ps1/.psm1/.psd1 files, and follows directory symlinks with no containment or cycle check. A single symlink pointing to the filesystem root — e.g. a standard Wine prefix inside the workspace, which always contains dosdevices/z: -> / — makes the walk effectively unbounded: PSES pins one CPU core at ~100% indefinitely and floods its log (~5 MB every 1–2 minutes) with Could not enumerate directories in the path '…' due to the path not being accessible warnings. Removing the symlink is not enough by itself — the already running enumeration never finishes; the session has to be restarted.

Environment

• Extension version: 2025.4.0
• VS Code version: 1.140.0
• OS version: macOS 26.7.1, arm64
• PowerShell version: 7.6.6

Repro

1. Put a standard Wine prefix inside the workspace (any folder where one runs/tests Windows tools; it does not even need to be tracked by git — the enumerator does not consult .gitignore):

   WINEPREFIX=<workspace>/Temp/wine-prefix wineboot --init
   ls -l <workspace>/Temp/wine-prefix/dosdevices
   # c: -> ../drive_c
   # z: -> /          <-- auto-created by wine for every prefix
   

2. Open the workspace in VS Code with the PowerShell extension and open any .ps1 file.

Observed

• The pwsh (PSES) process sits at ~100% of one core for hours (verified over 1.5 h; it had accumulated 72 minutes of CPU time by the time I sampled it).
• The PSES log rotates every 1–2 minutes at ~5 MB per file, almost entirely entries like:

  <Warning>Microsoft.PowerShell.EditorServices.Services.WorkspaceService: Could not enumerate directories in the path '/Users/…/Temp/wine-prefix/dosdevices/z:/…' due to the path not being accessible
  

  The logged paths show the walker descending into z: and re-entering the workspace through nested z: segments.
• sample <pid> shows a single .NET thread-pool worker spending ~100% of its samples in filesystem enumeration syscalls: SystemNative_OpenDir / SystemNative_ReadDir / SystemNative_Stat / SystemNative_LStat.

Root cause

• WorkspaceService.FollowSymlinks defaults to true, so EnumeratePSFiles() runs with ignoreReparsePoints: false and maxDepth: 64: WorkspaceService.cs.
• WorkspaceFileSystemWrapper.SafeEnumerateFileSystemInfos applies only that MaxRecursionDepth cap — the mitigation added in PowerShellEditorServices#795 for Process terminated bue to StackOverFlow - process terminated with code 3221225725 #1613: WorkspaceFileSystemWrapper.cs. A depth cap bounds nesting, but not breadth or revisits: a z: -> / link lets the walker enumerate the entire filesystem, and since / contains the workspace itself, the walk re-enters dosdevices/z: again and again up to the depth limit — in practice unbounded work on a real disk.

Workaround

rm "<workspace>/Temp/wine-prefix/dosdevices/z:"

then restart the session (PowerShell: Restart Current Session or reload the window). Wine itself works fine without the Z: drive, so the symlink can safely be deleted right after prefix creation (and re-deleted whenever the prefix is re-initialized).

Possible directions

• Don't follow directory symlinks whose resolved target is outside the workspace roots (containment check), and/or
• detect cycles (e.g. a visited (device, inode) set for symlinked directories), and/or
• default FollowSymlinks to false, or expose it as a user setting,
• optionally consult .gitignore — in my case the indexer burned a core over a Temp/ folder that git itself ignores.

Happy to test a build with any of these.