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