To qualify this a bit, the reference to longjmp() is kind of a red herring; in general the list of things you can do in a signal handler is very limited (as do

To qualify this a bit, the reference to longjmp() is kind of a red herring; in general the list of things you can do in a signal handler is very limited (as documented by signal-safety(7) that you reference.) longjmp() is just one prominent item on that list of things you can't (or shouldn't do.) None of the items on that list allow you to cleanly terminate the thread (you can send another signal to yourself or another thread, but that's only very conditionally helpful.) pthread_cancel() does the one and only sane thing - implement a flag mechanism that is checked in a bunch of well-specified places, and gated with an enable. Whether these well-specified places work for a particular application is definitely a tough question, but either way anything sane will be some type of "set flag and interrupt long-running (I/O) operations" combination.