ApsaraDB for Redis:Notice on update of StackExchange.Redis

Details

Impact scope

A timeout error occurs if all of the following conditions are met:

• The version of the StackExchange.Redis client is earlier than 2.7.20.

• The Redis instance is a cluster instance in proxy mode or a read/write splitting instance.

• The SELECT command is used to switch between multiple databases.

Sample error

1. StackExchange.Redis.RedisTimeoutException: Timeout performing xxx (5000ms), inst: 0, qu: 0, qs: 0, aw: False, rs: ReadAsync, ws: Idle, in: 0, in-pipe: 0, out-pipe: 0, serverEndpoint: XX.XX.XX.XX:6379, mgr: 10 of 10 available, clientName: 67c80fdab92d, PerfCounterHelperkeyHashSlot: 11235, IOCP: (Busy=0,Free=1000,Min=12,Max=1000), WORKER: (Busy=18,Free=32749,Min=12,Max=32767), v: xx.y.xx.xxx (Please take a look at this article for some common client-side issues that can cause timeouts: https://stackexchange.github.io/StackExchange.Redis/Timeouts)
2. Multiple databases are not supported on this server; cannot switch to database

Cause

Open source Redis clusters do not support multiple databases. You cannot run the SELECT command after you switch your instance from the master-replica architecture to the cluster architecture. However, ApsaraDB for Redis instances in proxy mode support multiple databases. The proxy mode allows you to run the SELECT command in a cluster or read/write splitting instance to switch to another database. You can use this feature to upgrade a standalone instance to a cluster or read/write splitting instance. For more information, see Features of proxy nodes.

StackExchange.Redis versions earlier than 2.7.20 misidentify proxy nodes of Alibaba Cloud Redis as clusters. As a result, the SELECT command cannot be run. This issue has been fixed in StackExchange.Redis 2.7.20.

Solution

Update StackExchange.Redis to 2.7.20 or later.

References

• Issues#2642

• PR#2646

• Features of proxy nodes

• Use a client to connect to an ApsaraDB for Redis instance