🐛 fix(unix): suppress EIO on close in Docker bind mounts#513
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gaborbernat merged 1 commit intotox-dev:mainfrom Mar 11, 2026
Merged
🐛 fix(unix): suppress EIO on close in Docker bind mounts#513gaborbernat merged 1 commit intotox-dev:mainfrom
gaborbernat merged 1 commit intotox-dev:mainfrom
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On macOS Docker with bind-mounted filesystems, the unlink-before-close sequence in _release() causes os.close(fd) to raise EIO. The unlink must stay before unlock to prevent a race where two processes lock different inodes, so we suppress OSError on close instead. At that point the lock is already released and POSIX guarantees the fd is invalidated regardless of the close return value. Fixes tox-dev#512
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Since 3.20.4, releasing a
UnixFileLockinside Docker on macOS with bind-mounted filesystems raisesOSError: [Errno 5] Input/output erroronos.close(fd). 🐛 The root cause is theunlink → flock unlock → closesequence in_release(): some FUSE-backed bind-mount drivers returnEIOwhen closing an fd whose directory entry was already removed.The
unlinkmust stay beforeunlockto prevent a race where a concurrent acquirer locks the old inode while a new file is created, so reordering is not an option. Instead,os.close(fd)is now wrapped insuppress(OSError), matching the existing treatment ofunlink. At that point the lock is already released and POSIX guarantees the fd is invalidated regardless of theclosereturn value, so suppressing the error is safe.Fixes #512