RedisOnlineStore missing async_supported property - server never uses async Redis path #6437

Summary

RedisOnlineStore implements full async support (online_read_async, online_write_batch_async, _get_client_async using redis.asyncio), but does not override the async_supported property from the base OnlineStore class. The default returns SupportedAsyncMethods(read=False, write=False), so the feature server never uses the async path.

Impact

In feature_server.py, the online read dispatch checks this property:

if store._get_provider().async_supported.online.read:
    response = await store.get_online_features_async(**read_params)
else:
    response = await run_in_threadpool(
        lambda: store.get_online_features(**read_params)
    )

Because async_supported.online.read is False for Redis, every request goes through run_in_threadpool(sync) instead of await get_online_features_async(). This means:

No non-blocking I/O — sync Redis calls block a thread from the threadpool instead of using redis.asyncio non-blocking pipeline
No parallel FeatureView reads — the base class get_online_features_async uses asyncio.gather() to query all FeatureViews concurrently, but the sync path reads them sequentially
Thread pool pressure — under concurrent load, the threadpool becomes a bottleneck since each request occupies a thread for the duration of the Redis call

DynamoDB and MongoDB already declare async_supported:

DynamoDBOnlineStore: SupportedAsyncMethods(read=True, write=True)
MongoDBOnlineStore: SupportedAsyncMethods(read=True, write=True)

Redis is the only online store with full async implementation that doesn't declare support.