fix(batcher): Reset lock and flusher in child after fork#6163
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ericapisani merged 7 commits intomasterfrom Apr 30, 2026
Merged
fix(batcher): Reset lock and flusher in child after fork#6163ericapisani merged 7 commits intomasterfrom
ericapisani merged 7 commits intomasterfrom
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Uses the same fix introduced in #6148 to prevent deadlocks in the monitor when os.fork() is called while another thread holds the monitor's lock. If os.fork() runs while another thread holds Batcher._lock, the child inherits the lock locked but the holding thread does not exist in the child, so the lock can never be released and _ensure_thread deadlocks forever. Register an after-fork hook via os.register_at_fork that replaces _lock with a fresh lock and resets _flusher / _flusher_pid in the child. Use a weakref to the batcher so the hook does not keep the instance alive. Move shared init out of SpanBatcher into the base Batcher.__init__ so all batchers (log, metrics, span) get the fork-safety hook from a single place. Fixes PY-2391 Fixes #6149
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…class from batcher but that will not be done in this set of changes. Update batcher deadlock fix to use weakmethod, to be consistent with the approach taken in monitor.py
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alexander-alderman-webb
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Apr 30, 2026
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Apply the same fork-safety fix introduced in #6148 (for the monitor) to all batchers (log, metrics, span).
If
os.fork()runs while another thread holdsBatcher._lock, the child inherits the lock locked but the holding thread does not exist in the child, so the lock can never be released and_ensure_threaddeadlocks forever. Register an after-fork hook viaos.register_at_forkthat replaces_lockwith a fresh lock and resets_flusher/_flusher_pidin the child. The hook holds aweakrefto the batcher so it does not keep the instance alive.Each batcher (log, metrics, span) gets a regression test that acquires the lock on the parent, forks, and asserts in the child that the lock object was replaced, the new lock is not held, and
_flusher/_flusher_pidwere reset. Tests are skipped on Windows and on Python builds withoutos.register_at_fork.Fixes PY-2391
Fixes #6149