Chapter 21

Intertask Communication

Signaling

Abstract

Signaling is an asynchronous interprocess communication mechanism in POSIX-compliant operating systems. In some sense, signals are the software equivalent of hardware interrupts. We introduce POSIX signals and the signal handling mechanism defined in the POSIX standard. As a related concept, POSIX spinlock is also briefly discussed. Examples are given to demonstrate how signals and spinlock objects can be used. Pulsing is an asynchronous notification mechanism implemented in QNX. A client process, via QNX synchronous message passing, can register a pulse event together with a firing condition to a server process. Whenever the firing condition occurs, the server may deliver the pulse event ...

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