Introduction - If you have any usage issues, please Google them yourself
Epoll is an improved poll for the Linux kernel to handle large batch file descriptors, an enhanced version of the multiplexed IO interface select/poll under Linux, which can significantly improve the application rate of the system CPU in a large number of concurrent connections in a large number of concurrent connections. Another reason is that when an event is obtained, it does not need to traverse the entire set of listener descriptors, just traversing the descriptor sets that are added to the Ready queue asynchronously by the kernel IO event. In addition to providing the level trigger (Level Triggered) of the select/poll IO event (Level Triggered), epoll provides the edge trigger (Edge Triggered), which makes the user space program likely to cache the IO state, reduce the call of the epoll_wait/epoll_pwait, and improve the efficiency of the application