Tair (Redis® OSS-Compatible):Upgrade StackExchange.Redis to version 2.7.20 or later

Details

Scope of impact

Timeout errors occur when all these conditions are met:

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

• The Tair instance uses cluster architecture with proxy mode or read/write splitting architecture.

• The application runs the SELECT command to switch databases.

Error examples

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 Cluster does not support multiple databases, so the SELECT command fails after migration from primary/standby to cluster architecture. However, the proxy mode of Tair (Redis OSS-compatible) supports multiple databases, enabling SELECT across cluster and read/write splitting architectures for smoother upgrades. Tair Proxy feature overview.

StackExchange.Redis versions earlier than 2.7.20 misidentify the proxy node of Tair as a standard cluster node, causing SELECT to fail. This is fixed in version 2.7.20.

Resolution

Upgrade StackExchange.Redis to version 2.7.20 or later.

References

• StackExchange/StackExchange.Redis#2642

• StackExchange/StackExchange.Redis#2646

• Tair Proxy feature overview

• Client connection tutorial