Performance bottleneck of Redis

[Kcser]

I am very interested in the bottleneck of Redis. It seems that the hash function or others are not the bottle neck as we can achieve better performance if we do use the -P parameters with pipeline. Furthermore, if we run both the server and the benchmark on the same physical machine, there will be less influence of the network. So what is the bottleneck for Redis at present? Is it the epoll/kqueue used?

[charsyam]

@Kcser Redis just can handle one command at a time.(It's single threaded)

[Kcser]

@charsyam The answer is true. However, if the bottleneck is the single thread, with a pipleline parameter -P, more than one commands are sent to the server at the same time. On the sever side, they are still executed one by one, while the performance with -P is much better than the commands without it (through redis-benchmark). So how can we explain the growth of performance with -P?

[badboy]

Pipelining avoids the round-trip to the client for every single command. This round-trip can be quite significant as you have seen in benchmarks.

There's no single answer to your question. Different use cases exhibit different bottlenecks, ranging from network bandwidth over CPU usage to memory usage. If you are experiencing a bottleneck in your own usage, it might be worthwhile to discuss it and look into how to improve it (by improving Redis or by improving your usage).

Keep in mind that this issue tracker should be used for bugs or improvements to the Redis server. For questions like yours please other mediums are better suited, such as the subreddit /r/redis, the mailing list or the irc channel #redis on freenode.

[Kcser]

@badboy Sorry,sir. I will post my question somewhere else. Thank you