Nix sometimes creates lock files that persist upon process death.

[elikoga]

Describe the bug

Nix sometimes creates lock files that persist upon process death.

I have encountered this on a colleagues system before sometimes, but not reproducibly.

Someone also encountered this on #de:nixos.org today (Jan 6)

Relevant line for the lock:

nix/src/libstore/build/derivation-goal.cc

Line 684 in daab4d1

fmt("waiting for lock on %s", Magenta(showPaths(lockFiles))));

This is unrelated to #1015 (different lock)

Steps To Reproduce

Expected behavior

Metadata

Additional context

Checklist

• checked latest Nix manual (source)
• checked open bug issues and pull requests for possible duplicates

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[Mic92]

The lock file might still exists but flock should still work regardless as it's based on the liveness of the lock holder process. It shouldn't matter for the correctness if the file exist. Are you sure the other process didn't exist at the time? This would be a kernel bug otherwise:

nix/src/libstore/unix/pathlocks.cc

Line 51 in 383ab87

while (flock(desc, type) != 0) {