How to increase Redis performance when 100% CPU? Sharding? Fastest .Net Client?

Question

Due to massive load increases on our website redis is now struggling with peak load because the redis server instance is reaching 100% CPU (on one of eight cores) resulting

Answer 1

My first, simple suggestion if you haven't done it already would be to turn off all RDB or AOF backups on your Master at the very least. Of course then your slaves might fall behind if they're still saving to disk. See this for an idea of the cost of RDB dumps

Another thing to do is to make sure you're pipelining all of your commands. If you're sending many commands individually that can be grouped into a pipeline you should see a bump in performance.

Also, this SO post has a good answer about profiling Redis

More info about your use case, and data structure would be helpful in deciding whether there's a simple change you could make to the way you're actually using Redis that would give you an improvement.

Edit: In response to your latest comment, it's good to note that every time you have a slave lose connection and reconnect, it will re-sync with the master. In previous versions of Redis this was always a complete re-sync, so it was quite expensive. Apparently in 2.8 the slave is now able to request a partial re-sync of just the data it's missed since it's disconnection. I don't know much about the details, but if either your master or any of your slaves aren't on 2.8.* and you have a shaky connection, that could really hurt your cpu performance by constantly forcing your master to re-sync the slaves. More info Here