Signals

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.