Why error No connection is available to service this operation: SETEX while writing to Redis Cache in C# console application and how to solve it

Question

I am trying to write records from a dictionary with around 5000 records to a Redis cache. But sometimes I get the below exception, I have no clue why I am getting this error, I have checked on the internet but could not find any solution or root cause of this issue.

using (ConnectionMultiplexer redis = ConnectionMultiplexer.Connect(_configuration.GetConnectionString("redis_server")))
            {
                IDatabase db = redis.GetDatabase();


                foreach (KeyValuePair<string, string> keyValuePair in _dictAllData)
                {
                    db.StringSet(keyValuePair.Key, keyValuePair.Value, TimeSpan.FromMinutes(30));
                }

        }

Exception

No connection is available to service this operation: SETEX 747712; IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=0,Free=32767,Min=4,Max=32767), Local-CPU: n/a

Edit:

StackExchange.Redis version: 2.0.601

Answer 1

Seems like you are running out of connections in the pool (client-side). Besides, performance-wise, one set at a time is bad in this case.

You should be using batching or pipelining. See Pipelining vs Batching in Stackexchange.Redis. It has code examples.

And since it seems you don't care about the response, consider flags: CommandFlags.FireAndForget. See Pipelines and Multiplexers.