semaphore

A global flag in the system that prevents activities from occurring at the same time. Each semaphore is a label that the system manages. Typically, a project or step that requires exclusive use of a resource obtains a semaphore to ensure that exclusive use.

You set a semaphore in a step by using the .semget command. It is released in a separate step by the .semput command. After you obtain the semaphore, no other step can get it. Steps that attempt to obtain the semaphore wait until it is released.

When a project completes, the system automatically releases any semaphores that the project used. Under some cases, for example when a job ends because of a system error, the semaphore is not released. In that case it can be manually released.


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