Interpretations

Answering questions that may arise related to the meaning of portions of an IEEE standard concerning specific applications.

IEEE Standards Interpretations for IEEE Std 1003.1c™-1995 IEEE Standard for Information Technology--Portable Operating System Interface (POSIX(R)) - System Application Program Interface (API) Amendment 2: Threads Extension (C Language)

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Interpretation Request #21
Topic: timers and SIGEV_THREAD Relevant Clauses: 14.2.2.2 (P1003.1b)

In P1003.1c D10, corresponding section in IEEE Std 1003.1b-1993 is 14.2.2.2 The behavior for timer_create() specifies what happens when a sigevent structure of type SIGEV_NONE or type SIGEV_SIGNAL is passed to the function. POSIX.1c does not specify what the behavior of this function is if the sigevent structure is for SIGEV_THREAD. The most complicated part is when sigevent specifies SIGEV_THREAD but the timer is a reloading timer so that it continually expires. What is supposed to happen with timers and SIGEV_THREAD?

A thread is to be created when the timer expires? What happens with reloading timers which continually expire? Does only one thread get created and from then on an overrun count is incremented? Since these threads are detached, you have no way of knowing this thread terminates in order to stop incrementing the count and create a new thread on the next timer expiration.

Interpretation Response
This is a duplicate. See Interpretation #3, part 13.

Rationale for Interpretation
None.