V2 Changes

Fixed: deadlock in Cluster.connect() failure path

Cluster.connect() acquires self._lock, and on control connection failure the original code called self.shutdown() inside the with self._lock: block. Since shutdown() also acquires self._lock, this would deadlock with a plain Lock (any network failure during initial connection would trigger it).

Fix: Restructured connect() to save the exception and call shutdown() after the with self._lock: block exits, avoiding the re-entrant acquisition.

Additional cleanup:

• Removed unused RLock import from cassandra/connection.py
• Added TestClusterConnectFailureNoDeadlock test that verifies connect() calls shutdown() and re-raises without deadlocking when using a plain Lock

Tests: 683 unit tests pass (660 core + 23 IO), 0 failures.

Follow-up: Skip lock acquisition when no orphaned requests in process_msg

Commit: 2e5a6c6

What changed

In process_msg(), the orphaned request check acquires a lock on every response to check self.orphaned_request_ids. Since orphaned requests only exist after timeouts (a rare event), the set is almost always empty.

Now we check if self.orphaned_request_ids: (set truthiness) before acquiring the lock. Empty set → skip the lock entirely.

Thread safety

The unlocked truthiness check on a set is safe under the GIL (atomic read of internal size field). Worst case:

• False positive (set non-empty but stream_id not in it): enters lock block, re-checks, safe
• False negative (set just got an entry): orphaned response processed normally — acceptable

Benchmark results (Python 3.14, 2M iterations)

Testing

• 617 unit tests passed (10.4s)
• No regressions