fix: Cap the sync Redis feature store upsert retry loop at 10 attempts

Author: jsonbailey

ldclient/impl/integrations/redis/redis_feature_store.py

@@ -15,6 +15,9 @@
 except ImportError:
     pass
 
+# Cap the WATCH-retry loop so a hot-contended key can't starve upsert_internal forever; matches the LaunchDarkly Go Redis stores.
+_MAX_UPSERT_RETRIES = 10
+
 
 class _RedisFeatureStoreCore(DiagnosticDescription, FeatureStoreCore):
     def __init__(self, url, prefix, redis_opts: Dict[str, Any]):
@@ -82,7 +85,7 @@ def upsert_internal(self, kind, item):
         key = item['key']
         item_json = json.dumps(item)
 
-        while True:
+        for _ in range(_MAX_UPSERT_RETRIES):
             pipeline = r.pipeline()
             pipeline.watch(base_key)
             old = self.get_internal(kind, key)
@@ -111,6 +114,8 @@ def upsert_internal(self, kind, item):
                     continue
             return item
 
+        raise RuntimeError("failed to update key %s in '%s' after %d attempts" % (key, kind.namespace, _MAX_UPSERT_RETRIES))
+
     def initialized_internal(self):
         r = redis.Redis(connection_pool=self._pool)
         return r.exists(self._init_key)