mirror of
https://github.com/OpenMP/Examples.git
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42 lines
926 B
C
42 lines
926 B
C
/*
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* @@name: acquire_release.4.c
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* @@type: C
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* @@compilable: yes, omp_5.0
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* @@linkable: yes
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* @@expect: success
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*/
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#include <stdio.h>
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#include <omp.h>
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int main()
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{
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// !!! THIS CODE WILL FAIL TO PRODUCE CONSISTENT RESULTS !!!!!!!
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// !!! DO NOT PROGRAM SYNCHRONIZATION THIS WAY !!!!!!!
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int x = 0, y;
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#pragma omp parallel num_threads(2)
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{
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int thrd = omp_get_thread_num();
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if (thrd == 0) {
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#pragma omp critical
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{ x = 10; }
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// an explicit flush directive that provides
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// release semantics is needed here
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// to complete the synchronization.
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#pragma omp atomic write
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y = 1;
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} else {
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int tmp = 0;
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while (tmp == 0) {
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#pragma omp atomic read acquire // or seq_cst
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tmp = y;
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}
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#pragma omp critical
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{ printf("x = %d\n", x); } // !! NOT ALWAYS 10
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}
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}
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return 0;
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}
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