clearInterval() stops future heartbeat ticks but not one already in
flight: a straggler tick past its ownership guards could land its
atomic lock rewrite AFTER releaseWriterLock()'s unlink, re-creating
the lock file as a phantom that blocks the next writer until the
stale TTL expires (~60s) — the pool-eviction reopen case. Found as an
ENOENT heartbeat warning during benchmark teardown; the quiet variant
is the harmful one.
releaseWriterLock() now awaits the in-flight tick (tracked per tick,
self-clearing) before reading/unlinking, so a straggler's write always
lands BEFORE the unlink and gets removed with everything else. The
heartbeat's ENOENT is also now benign-by-contract (lock or directory
removed under us — the next acquire recreates it); other errors stay
loud.
Pin: straggler-past-guards simulation — lock file absent after close,
directory immediately claimable (fails on the undrained code).
David Snelling
70e4bc8a79