multi-threaded signal handling

Question

1. In unix, If a multi-threaded process was sent a signal, which thread will be the one to execute the handling function?

2. if it is a multi-cpu machine, more than 1 thread is running at the same time. which thread will be the on to run the signal handling function?

Answer 1

According to man 7 signal, all threads in the process share the same signal handler, and if a signal is delivered to a process with multiple threads that have not blocked the signal, one of them is arbitrarily chosen to receive it.

Having a multi-CPU machine will not change these semantics.