[quietbritishjim]

A separate thread with sigwait() may be easier. Though I must admit, I've rarely had to do that manually, as I'm usually using a language or framework that gives an easier way to get notified about signals (e.g. Python KeyboardInterrupt or listeners in Boost ASIO or libuv). Aside from saving some boilerplate, those also emulate equivalent signals in Windows.

Threads waiting on event loops is exactly what you want on shutdown: that's what you use to notify them to exit.

[cryptonector]

I never use sigwait() or sigsuspend() -- I just have signal handlers that write a byte (e.g., the signal number) into a pipe, and maybe they set a global volatile sig_atomic_t variable. DJB calls this a "self-pipe". A self-pipe turns signals into I/O events that select/poll/epoll/event ports/kqueue/io_ring/whatever can handle like any other events.

At exit time I just make sure every thread can get an event. The main thread can pthread_cond_wait() for all the other threads to exit, waiting for the count of them to fall to zero.

[quietbritishjim]

Ah self pipe is a good idea, I suspect that's what those async frameworks are doing under the hood.