How to properly use redis with servicestack in a multi-thread environment? - multithreading

Question

I assumed that we should use basicredisclientmanager or pooledredisclientmanager?
I tried this
private void dddddd()
{
for(int i=0;i<=1000;i++)
{
var client = new BasicRedisClientManager(new string[] { "host1", "host2", "host3" }).GetClient();
//do something with client
}
}
This loop runs fine for the first 100 plus but after that, I always got an error "Unknown Command Role"?? What is that and how to fix it? I need help!
I also tried to make a new class called MyRedisMgr and created a static property to create some sort of singleton but it didn't work either.
public BasicRedisClientManager MyMgr = new BasicRedisClientManager(new string[] { "host1", "host2", "host3" });
And then I use it like
for(int i=0;i<=1000;i++)
{
var client = MyRedisMgr.MyMgr.GetClient();
//do something with client
}

Answer 1

Please read the documentation on the proper usage of Redis Client Manager which should only be used as a singleton.
The BasicRedisClientManager doesn't have any connection pooling so every time you call GetClient() you're opening a new TCP connection with the redis-server. Unless you understand the implications you should be using one of the Pooled Redis Client Managers, e.g: RedisManagerPool.
You also need to always dispose the client after its used so that it can either be re-used or the TCP connection disposed of properly.
So your code sample should look like:
//Always use the same singleton instance of a Client Manager
var redisManager = new RedisManagerPool(masterHost);
for(int i=0;i<=1000;i++)
{
using (var redis = redisManager.GetClient())
{
//do something with client
}
}
The "Unknown Command Role" error is due to using an old version of Redis Server. The ROLE command was added in redis 2.8.12 but this API should only be used if your using redis-server v2.8.12+, so you shouldn't be getting this error by default. You can avoid this error by upgrading to either the stable v3.0 or old 2.8 versions of redis-server which has this command.
If you want to continue using an older version, use the INFO command to check what version you're running then tell ServiceStack.Redis what the version is with:
RedisConfig.AssumeServerVersion = 2600; //e.g. v2.6
RedisConfig.AssumeServerVersion = 2612; //e.g. v2.6.12