The lifetime of a signal is the interval between its generation and its delivery. A signal that has been generated but not yet delivered is pending . There may be considerable time between signal generation and signal delivery. VxWorks supports a software signal facility. The signals asynchronously alter the control flow of task.
Any task can raise a signal for a particular task.
The task being signaled immediately suspends its current thread of execution and the task specified signal handler routine is executed the next time the task is scheduled to run. The signal handler gets invoked even if the task is blocked on some action or event. The signal handler is a user supplied routine that is bound to a specific signal and performs whatever actions are necessary whenever the signal is received. Signals are most appropriate for error and exception handling, rather than general intertask communication. Your application should use only one interface and not mix the two.