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The notion of using a semaphore in software as a means of mutual exclusion was invented by the Dutch computer scientist Edgser Dijkstra in 1959. In computer software, a semaphore is a protocol mechanism offered by most multitasking kernels. Semaphores, originally used to control access to shared resources, but now they are used for synchronization as described in Chapter 14, “Synchronization” Synchronization. However, it is useful to describe how semaphores can be used to share resources. The pitfalls of semaphores will be discussed in a later section.
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