libev

libev is a free, high-performance, non-blocking I/O event loop library written in C. Its primary purpose is to provide a framework for handling asynchronous I/O operations efficiently. It is designed to be small, fast, and portable, making it suitable for a wide range of applications, particularly those requiring high concurrency and low latency.

The library offers a unified interface for monitoring various types of events, including file descriptor I/O, timers, child process status changes, and signals. libev uses the most efficient underlying I/O notification mechanism available on the operating system, such as epoll on Linux, kqueue on BSD and macOS, and IOCP on Windows. This adaptability ensures optimal performance across different platforms.

Key features of libev include its minimal footprint, low overhead, and a clean API. It allows developers to write event-driven programs without managing complex state machines or dealing directly with low-level OS-specific APIs. Applications built with libev can handle thousands of concurrent connections with relatively modest resource consumption. It is widely used in network servers, daemons, and other performance-critical software.