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24 lines
1013 B
TeX
24 lines
1013 B
TeX
\pagebreak
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\chapter{Ownership of Locks}
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\label{chap:lock_owner}
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Ownership of locks has changed since OpenMP 2.5. In OpenMP 2.5, locks are owned
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by threads; so a lock released by the \code{omp\_unset\_lock} routine must be
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owned by the same thread executing the routine. With OpenMP 3.0, locks are owned
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by task regions; so a lock released by the \code{omp\_unset\_lock} routine in
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a task region must be owned by the same task region.
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This change in ownership requires extra care when using locks. The following program
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is conforming in OpenMP 2.5 because the thread that releases the lock \code{lck}
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in the parallel region is the same thread that acquired the lock in the sequential
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part of the program (master thread of parallel region and the initial thread are
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the same). However, it is not conforming in OpenMP 3.0 and 3.1, because the task
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region that releases the lock \code{lck} is different from the task region that
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acquires the lock.
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\cexample{lock_owner}{1c}
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\fexample{lock_owner}{1f}
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