fix(consensus): replace non-reentrant Lock with RLock in CircuitBreaker (#332) - #343
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Fixes #332 - Replace threading.Lock with threading.RLock in CircuitBreaker._lock. Previously, record_success and record_failure acquired self._lock and then called get_health() which re-entered self._lock, causing an immediate self-deadlock on the event-loop thread. - Add with self._lock to get_all_health for thread-safe iteration over _engines. - Add regression tests in tests/test_circuit_breaker_deadlock_332.py covering: - record_success and record_failure without deadlock - Circuit transition to OPEN, DEGRADED, and HEALTHY - Thread-safe get_all_health statistics - Concurrent multi-threaded access without deadlock
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Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review. 📝 WalkthroughWalkthroughChangesCircuitBreaker synchronization
Estimated code review effort: 3 (Moderate) | ~15 minutes Merge Risk: ⚪ Minimal · up to The PR replaces a self-deadlocking lock with a reentrant lock and protects shared health metrics, with regression coverage reported as passing. No actionable merge-blocking risk remains beyond normal checks and review. 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Description checkExplanation The description explains the root cause, implementation changes, and test results. It does not include the required QWED Enforcement Checklist or a Notes section that explains compliance with QWED_RULES.md. Full details: Linked Issues checkExplanation The changes satisfy issue Full details: Out of Scope Changes checkExplanation The changes remain within scope. The get_all_health() locking, public reset() method, reset delegation, and concurrency tests support CircuitBreaker synchronization and regression coverage for issue
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Inline comments:
In `@tests/test_circuit_breaker_deadlock_332.py`:
- Around line 23-41: Update the recovery test around CircuitBreaker to remove
the fractional recovery interval and time.sleep call. Inject a controlled clock
for qwed_new.core.consensus_verifier.time.time, then explicitly advance that
clock past the recovery threshold before performing the recovery assertion,
preserving deterministic fail-closed behavior.
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src/qwed_new/core/consensus_verifier.pytests/test_circuit_breaker_deadlock_332.py
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Greptile SummaryCircuitBreaker now uses re-entrant synchronization for nested health updates and protects availability checks, health snapshots, and resets under the same lock. Focused validation exercised the prior deadlock path and concurrent circuit operations successfully. Confidence Score: 5/5No blocking failure remains: nested health updates, recovery transitions, snapshots, resets, and concurrent access completed without deadlock or errors. No accepted blocking findings remain after exercising the affected CircuitBreaker behavior.
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…onization - Enclose is_available() read, timeout check, and state transition within with self._lock to ensure atomic state updates under concurrency. - Add CircuitBreaker.reset() under lock and delegate ConsensusVerifier.reset_circuit_breakers() to it for thread-safe dictionary clearance. - Replace wall-clock time.sleep with monkeypatched deterministic clock in recovery tests. - Remove unused imports (pytest, EngineHealth) in test_circuit_breaker_deadlock_332.py. - Add unit test for thread-safe reset() and reset_circuit_breakers().
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Inline comments:
In `@tests/test_circuit_breaker_deadlock_332.py`:
- Around line 7-11: Update the direct deadlock tests around
test_circuit_breaker_record_success_no_deadlock and the corresponding
record_failure case to execute each circuit-breaker call in a daemon worker
thread, join with a bounded timeout, and assert the worker completed. Capture
any exception raised by the worker and assert or re-raise it after joining so
callback failures remain visible instead of being swallowed.
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src/qwed_new/core/consensus_verifier.pytests/test_circuit_breaker_deadlock_332.py
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- Run direct CircuitBreaker deadlock probes in daemon threads with a bounded timeout via _run_with_timeout. - Capture and re-raise any worker thread exceptions to ensure failures remain visible.
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2 participants
Fixes #332
Summary & Root Cause
In
src/qwed_new/core/consensus_verifier.py,CircuitBreakerinitialized its internal lock as a non-reentrantthreading.Lock()(self._lock = threading.Lock()).Both
record_successandrecord_failureacquiredself._lockand immediately calledself.get_health(), which attempted to re-acquire the exact same lock:Because
threading.Lock()cannot be re-entered by the owning thread, any call to/verify/consensuscaused an immediate self-deadlock on the event-loop thread, permanently hanging the whole service.Changes
self._lock = threading.Lock()withself._lock = threading.RLock()inCircuitBreaker.__init__.with self._lock:insideget_all_health()to prevent concurrent dictionary size mutation issues when iterating over_engines.tests/test_circuit_breaker_deadlock_332.pywith 4 tests:test_circuit_breaker_record_success_no_deadlock: Verifiesrecord_successcompletes without deadlock.test_circuit_breaker_record_failure_no_deadlock: Verifies state transitions (HEALTHY→OPEN→DEGRADED→HEALTHY) after recovery timeouts.test_circuit_breaker_get_all_health_thread_safe: Verifies metrics dictionary extraction under lock.test_circuit_breaker_concurrent_access: Stress-tests 10 concurrent worker threads making 500 calls across multiple engines without deadlocks or exceptions.Test Verification
pytest tests/test_circuit_breaker_deadlock_332.py -v: 4/4 PASSED (0.32s)tests/test_pr114_regressions.py,tests/test_pr115_regressions.py,tests/test_pr117_regressions.py,tests/security/test_hybrid_advisory_only.py): 108/108 PASSED (38.31s)Summary by CodeRabbit
Bug Fixes
Tests