Tip: Child processes inherit signal handlers from the parent, so a parent should not set up handlers prior to sproc() or fork() unless they are meant to be inherited. The FRS control process for a synchronized Frame Scheduler should have handlers for Underrun and Overrun signals. The handler could report the error and issue frs_destroy() to shut down its scheduler. An FRS controller for a synchronized scheduler should use the default action for SIGHUP (Exit) so that completion of the frs_destroy() quietly terminates the FRS controller.
The FRS controller for the master (or only) Frame Scheduler should catch Underrun and Overrun exceptions, report them, and shut down its scheduler.
When an FRS is terminated with frs_destroy(), it sends SIGKILL to its FRS control process. This cannot be changed; and SIGKILL cannot be handled. Hence frs_destroy() is equivalent to termination for the FRS control process. (In the first release, the FRS sent SIGHUP, but this made deadlocks possible and had to be given up.)