Redis Architecture
The secret to Redis's incredible speed lies in its simple yet powerful architecture. It's essentially a single-threaded event loop that handles thousands of requests per second.
The Event Loop Visualized
How Redis processes requests from multiple clients using a single thread.
Redis Internal Flow
Event Loop
Redis uses its own event library called
ae. It's an efficient wrapper around epoll, kqueue, or select depending on the OS.Multiplexing
Instead of blocking on a single client, Redis watches thousands of sockets simultaneously and only processes those that have new data available.
Why Single Threaded?
No Context Switching
Avoids the overhead of switching between multiple CPU threads.
No Locks
Since only one thread modifies data, there's no need for expensive locking mechanisms like mutexes.
Memory Bound
Redis performance is usually limited by memory bandwidth, not CPU. A single fast thread is often enough.
Pro Tip:Since Redis 6.0, I/O threads can handle networking in parallel, but command execution remains atomic and single-threaded.