是否可以在进程中的所有线程上设置pthread_sigmask？

Question

This is a follow-up to this question and I have looked at the related questions.

I am still attempting to do some cleanup when SIGTERM is received, and then achieve the effect of TERM which is the default behavior when no thread in a process is waiting for a signal, and and no signal handler is defined.

In the earlier question, I had assumed that signals had deterministic behavior in a multithreaded application, but after some non-deterministic results and some research, I realized that this is not a safe assumption.

My application is multithreaded and using a normal signal handler via sigaction or signal has non-deterministic results because the arbitrary choice of which thread is actually interrupted to run the signal handler matters to the signal handler's operation (it is cleaning up some threads which might deadlock if the wrong thread is interrupted).

Therefore, I switched to doing synchronous signal handling . In particular, I am blocking SIGTERM using pthread_sigmask in the starting thread, and then calling sigwait() in the thread that will actually perform the cleanup. However, after sigwait() returns in the thread, and I finish my cleanup, I then try the following:

kill(getpid(), SIGTERM);

However, this signal is obviously ignored, because all the other active threads are blocking SIGTERM . Thus, I need to unblock signals in all other threads, before returning from the function that my cleanup thread is running. Is there a function call that can be used to set pthread_sigmask on other threads?

Answer 1

There is no call that can be used to set signal mask on other threads. Received signal is a trigger and no sense to resend that signal for itself. Try to use pthreads condition variables instead.