69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
/******************************************************************************
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* FILE: omp_bug5.c
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* DESCRIPTION:
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* Using SECTIONS, two threads initialize their own array and then add
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* it to the other's array, however a deadlock occurs.
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******************************************************************************/
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#include <omp.h>
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#include <stdio.h>
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#include <stdlib.h>
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#define N 1000000
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#define PI 3.1415926535
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#define DELTA .01415926535
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int main(int argc, char *argv[]) {
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int nthreads, tid, i;
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float a[N], b[N];
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omp_lock_t locka, lockb;
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/* Initialize the locks */
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omp_init_lock(&locka);
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omp_init_lock(&lockb);
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/* Fork a team of threads giving them their own copies of variables */
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#pragma omp parallel shared(a, b, nthreads, locka, lockb) private(tid)
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{
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/* Obtain thread number and number of threads */
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tid = omp_get_thread_num();
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#pragma omp master
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{
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nthreads = omp_get_num_threads();
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printf("Number of threads = %d\n", nthreads);
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}
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printf("Thread %d starting...\n", tid);
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#pragma omp barrier
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#pragma omp sections nowait
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{
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#pragma omp section
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{
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printf("Thread %d initializing a[]\n", tid);
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omp_set_lock(&locka);
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for (i = 0; i < N; i++)
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a[i] = i * DELTA;
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omp_set_lock(&lockb);
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printf("Thread %d adding a[] to b[]\n", tid);
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for (i = 0; i < N; i++)
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b[i] += a[i];
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omp_unset_lock(&lockb);
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omp_unset_lock(&locka);
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}
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#pragma omp section
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{
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printf("Thread %d initializing b[]\n", tid);
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omp_set_lock(&lockb);
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for (i = 0; i < N; i++)
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b[i] = i * PI;
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omp_set_lock(&locka);
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printf("Thread %d adding b[] to a[]\n", tid);
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for (i = 0; i < N; i++)
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a[i] += b[i];
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omp_unset_lock(&locka);
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omp_unset_lock(&lockb);
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}
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} /* end of sections */
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} /* end of parallel region */
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}
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