fix: keep a failed lock release from masking cancellation (#29979)

When Redis is unreachable at shutdown, the socket cleanup tasks do not stop. release_lock is a bare eval called from the finally of both periodic_session_pool_cleanup and periodic_usage_pool_cleanup, so it raises there and replaces the CancelledError already in flight. The usage task's except Exception then catches the Redis error and carries on reaping after shutdown cancelled it, and the session task ends with a ConnectionError in place of its cancellation.

release_lock now logs the failure and returns. aquire_lock sets the key with ex=self.timeout_secs and renew_lock re-expires it with the same value, so a release that never lands costs at most one lock timeout before another node can take over.

The except names both RedisClusterException and RedisError because the cluster-only types subclass Exception directly, and redis_cluster is a supported configuration, so RedisError alone would miss the outage on a cluster. Genuine bugs still propagate.

Verified against a real Redis: acquire, refusal while held, renew, compare-and-delete release and non-owner release are unchanged, a populated pool reaps identically with identical lock TTL lifecycles, and both tasks now cancel cleanly where before one kept running and the other died with the wrong exception.

backend/open_webui/socket/utils.py

@@ -3,12 +3,16 @@
 from __future__ import annotations
 
 import hashlib
+import logging
 import uuid
 
 import pycrdt as Y
 from open_webui.env import REDIS_KEY_PREFIX
 from open_webui.utils.json_codec import JSONCodec
 from open_webui.utils.redis import get_redis_connection
+from redis.exceptions import RedisClusterException, RedisError
+
+log = logging.getLogger(__name__)
 
 YDOC_KEY_PREFIX = f'{REDIS_KEY_PREFIX}:ydoc:documents'
 SCAN_BATCH_SIZE = 200
@@ -58,7 +62,10 @@ class RedisLock:
         return bool(self.redis.eval(self._RENEW_SCRIPT, 1, self.lock_name, self.lock_id, self.timeout_secs))
 
     def release_lock(self):
-        self.redis.eval(self._RELEASE_SCRIPT, 1, self.lock_name, self.lock_id)
+        try:
+            self.redis.eval(self._RELEASE_SCRIPT, 1, self.lock_name, self.lock_id)
+        except (RedisClusterException, RedisError) as e:
+            log.warning('Failed to release lock %s; it expires on its own: %s', self.lock_name, e)
 
 
 class RedisDict: