What does redis single thread mean?

The official FAQ states that because Redis is a memory-based operation, the CPU is not the bottleneck of Redis. The bottleneck of Redis is most likely the size of the machine memory or the network bandwidth. Since single-threading is easy to implement and the CPU will not become a bottleneck, it is logical to adopt the single-threaded solution (Recommended learning: Redis video tutorial)

See By this point, you may cry! I thought there would be some major technical points that make Redis so fast using a single thread, but I didn't expect an official answer that seemed to fool us! However, we can already clearly explain why Redis is so fast, and precisely because it is already fast in single-threaded mode, there is no need to use multi-threading!

However, our single-threaded approach cannot take advantage of multi-core CPU performance, but we can improve it by opening multiple Redis instances on a single machine!

Warning 1:The single thread we have been emphasizing here only has one thread to process our network requests. When a formal Redis Server is running, there must be more than one thread. It’s a thread, everyone needs to pay clear attention here! For example, when Redis is persisted, it will be executed as a sub-process or sub-thread (the specific sub-thread or sub-process needs to be studied in depth by the reader); for example, I checked the Redis process on the test server weapon, and then found the thread under the process:

The "-T" parameter of the ps command indicates Show threads, possibly with SPID column. The "SID" column indicates the thread ID, and the "CMD" column Thread name is shown.

Warning 2: The last paragraph in the FAQ in the above picture states that multi-threading will be supported starting from Redis 4.0 version, but only multi-threading is performed on certain operations. operation! Therefore, whether this article will still be single-threaded in future versions requires readers to verify!

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