Threads should call sigaction( ) to establish per-thread handlers for synchronous signals. The DCE Threads sigaction( ) function only modifies the signal action behavior for the calling thread and only works for synchronous signals. Threads must not use sigaction( ) for asynchronous signals.
Signal handlers should be careful in the actions they perform. In general, synchronous signal handlers should attempt to clean up and allow the thread to terminate. It is not advisable to attempt to continue after errors such as a segment violation, illegal instruction, and the like.
In general, the threads routines cannot safely be called within a signal handler. Furthermore, runtime libraries cannot reliably be used in signal handlers.