StackExchange.Redis.RedisTimeoutException: The timeout was reached before the message could be written to the output buffer, and it was not sent

Question

String: 70036 01:11:34 ERROR GetItemFromSessionStore => StackExchange.Redis.RedisTimeoutException: The timeout was reached before the message could be written to the output buffer, and it was not sent (5000ms, inst=37, qs=37, in=29426, active=EVAL), inst: 37, qs: 37, in: 0, serverEndpoint: Unspecified/***redis.redis.cache.windows.net:6380, mgr: 10 of 10 available, clientName: ******, IOCP: (Busy=3,Free=997,Min=4,Max=1000), WORKER: (Busy=5582,Free=27185,Min=5680,Max=32767), v: 2.0.519.65453 (Please take a look at this article for some common client-side issues that can cause timeouts: https://stackexchange.github.io/StackExchange.Redis/Timeouts) at StackExchange.Redis.ConnectionMultiplexer.ExecuteSyncImpl[T](Message message, ResultProcessor`1 processor, ServerEndPoint server) in C:\projects\stackexchange-redis\src\StackExchange.Redis\ConnectionMultiplexer.cs:line 2175 at StackExchange.Redis.RedisBase.ExecuteSync[T](Message message, ResultProcessor1 processor, ServerEndPoint server) in C:\projects\stackexchange-redis\src\StackExchange.Redis\RedisBase.cs:line 54 at StackExchange.Redis.RedisDatabase.ScriptEvaluate(String script, RedisKey[] keys, RedisValue[] values, CommandFlags flags) in C:\projects\stackexchange-redis\src\StackExchange.Redis\RedisDatabase.cs:line 1134

We are getting a lot of these errors when we get a surge of requests. We did have CPU and very high thread count when the timeout exceptions were logged.

Based on the documentation,

qsQueue-Awaiting-Response : {int}There are x operations currently awaiting replies from redis server.

inInbound-Bytes : {long}there are x bytes waiting to be read from the input stream from redis

Redis server seems to be handling the load well. So can someone explain what the error means?

Wiedmann

Were you able to solve this issue? – Inventor

Answer 1

Yes, likely thread starvation. You can set the minimum threshold so it doesn't run out of threads. The basic theory is the OS has to wait, like 500 ms, before it can spin up another thread after it reaches the minimum threshold.

ThreadPool.SetMinThreads(minWorker, minIoc)

https://learn.microsoft.com/en-us/dotnet/api/system.threading.threadpool.setminthreads?view=net-6.0

Sixteenmo

Answer 2

Make sure your Redis is up and running.

In my case I just forgot to run Redis as Docker container before I ran my application.

Chinquapin