fix: use RLock to prevent deadlock in database singleton initialization#654
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fix: use RLock to prevent deadlock in database singleton initialization#654
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get_engine() and get_session_factory() share the same threading.Lock(). When SessionLocal() is the first DB call (before get_engine() has been called independently), get_session_factory() acquires the lock then calls get_engine() which tries to acquire the same non-reentrant lock, causing a deadlock. This was masked in the OSS app because _verify_database() in the lifespan always calls get_engine() first. Premium (and any other consumer that calls SessionLocal() without a prior get_engine()) hits the deadlock on startup. Switching to RLock (reentrant) allows the nested acquisition to succeed. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Description
get_engine()andget_session_factory()inbackend/app/database.pyshare the samethreading.Lock(). WhenSessionLocal()is the first DB call (both singletons uninitialized),get_session_factory()acquires the lock then callsget_engine(), which tries to acquire the same non-reentrant lock, causing a deadlock.This was masked in the OSS app because
_verify_database()in the lifespan always pre-initializesget_engine(), but any consumer that callsSessionLocal()beforeget_engine()(e.g. clawbolt-premium) deadlocks on startup.Fix: switch
threading.Lock()tothreading.RLock()(reentrant) so nested acquisition by the same thread succeeds.Type
Checklist
uv run pytest -v)ruff check backend/ && ruff format --check backend/)AI Usage
Claude Code diagnosed the deadlock root cause through systematic middleware/request stack analysis and implemented the fix.