Event Loops

2 articles

Linux 04 Sep 2026 11 min read

Integrate Timers into Linux Event Loops with timerfd

Event loops work best when unrelated kinds of work have one common waiting mechanism. Sockets become readable. Pipes become writable. A child-process descriptor or signal descriptor can become ready. Timers are often the awkward exception. A program can call sleep() or nanosleep(), but that blocks the thread instead of letting it wait for I/O. It can pass a timeout to poll() or epoll_wait(), but one timeout becomes difficult to manage when the program has several independent deadlines. Traditional POSIX timers can deliver signals, which introduces a second asynchronous control path.

Linux Timers

Linux 04 Sep 2026 9 min read

Handle Linux Signals in Event Loops with signalfd

Unix signals are asynchronous by design: a signal can interrupt a program between ordinary instructions and transfer control to a signal handler. That model is useful, but it creates an awkward boundary for event-driven programs. A network server may already spend most of its time inside poll(), epoll_wait(), or another readiness API. Its sockets, pipes, and timers appear as file-descriptor events, while SIGTERM and SIGHUP arrive through a separate execution path with much stricter rules about what code may safely run.

Linux Signals