Redis performance on a multi core CPU

Question

I am looking around redis to provide me an intermediate cache storage with a lot of computation around set operations like intersection and union.

I have looked at the redis website, and found that the redis is not designed for a multi-core CPU. My question is, Why is it so ?

Also, if yes, how can we make 100% utilization of CPU resources with redis on a multi core CPU's.

Answer 1

I have looked at the redis website, and found that the redis is not designed for a multi-core CPU. My question is, Why is it so?

It is a design decision.

Redis is single-threaded with epoll/kqueue and scales indefinitely in terms of I/O concurrency. --@antirez (creator of Redis)

A reason for choosing an event-driven approach is that synchronization between threads comes at a cost in both the software (code complexity) and the hardware level (context switching). Add to this that the bottleneck of Redis is usually the network or the *memory, not the CPU. On the other hand, a single-threaded architecture has its own benefits (for example the guarantee of atomicity).

Therefore event loops seem like a good design for an efficient & scalable system like Redis.

Also, if yes, how can we make 100% utilization of CPU resources with redis on a multi core CPU's.

The Redis approach to scale over multiple cores is sharding, mostly together with Twemproxy.

However if for some reason you still want to use a multi-threaded approach, take a look at Thredis but make sure you understand the implications of what its author did (you can not use it as a replication master, for instance).

Answer 2

Redis server is a single threaded. But it allows to achieve 100% utilization of CPU resources using Redis nodes (master and/or slave).

1. Read operations could be scaled using Redis master/slave configuration with single master. One of CPU core used for master node and all others for slaves.

2. Write operations could be scaled using Redis multi-master cluster configuration. Multiple CPU cores used for master nodes and all others for slaves.

Redisson - Redis Java client which provides full support of Redis cluster. Works with AWS Elasticache and Azure Redis Cache. It includes master/slave discovery and topology update.