private (OpenMP)
Especifica que cada subproceso debe tener una instancia de una variable.
private(var)
Comentarios
donde
- var
la variable para tener instancias en cada subproceso.
Comentarios
private se aplica a las siguientes directivas:
Para obtener más información, vea Private de 2.7.2.1.
Ejemplo
// openmp_private.c
// compile with: /openmp
#include <windows.h>
#include <assert.h>
#include <stdio.h>
#include <omp.h>
#define NUM_THREADS 4
#define SLEEP_THREAD 1
#define NUM_LOOPS 2
enum Types {
ThreadPrivate,
Private,
FirstPrivate,
LastPrivate,
Shared,
MAX_TYPES
};
int nSave[NUM_THREADS][MAX_TYPES][NUM_LOOPS] = {{0}};
int nThreadPrivate;
#pragma omp threadprivate(nThreadPrivate)
#pragma warning(disable:4700)
int main() {
int nPrivate = NUM_THREADS;
int nFirstPrivate = NUM_THREADS;
int nLastPrivate = NUM_THREADS;
int nShared = NUM_THREADS;
int nRet = 0;
int i;
int j;
int nLoop = 0;
nThreadPrivate = NUM_THREADS;
printf_s("These are the variables before entry "
"into the parallel region.\n");
printf_s("nThreadPrivate = %d\n", nThreadPrivate);
printf_s(" nPrivate = %d\n", nPrivate);
printf_s(" nFirstPrivate = %d\n", nFirstPrivate);
printf_s(" nLastPrivate = %d\n", nLastPrivate);
printf_s(" nShared = %d\n\n", nShared);
omp_set_num_threads(NUM_THREADS);
#pragma omp parallel copyin(nThreadPrivate) private(nPrivate) shared(nShared) firstprivate(nFirstPrivate)
{
#pragma omp for schedule(static) lastprivate(nLastPrivate)
for (i = 0 ; i < NUM_THREADS ; ++i) {
for (j = 0 ; j < NUM_LOOPS ; ++j) {
int nThread = omp_get_thread_num();
assert(nThread < NUM_THREADS);
if (nThread == SLEEP_THREAD)
Sleep(100);
nSave[nThread][ThreadPrivate][j] = nThreadPrivate;
nSave[nThread][Private][j] = nPrivate;
nSave[nThread][Shared][j] = nShared;
nSave[nThread][FirstPrivate][j] = nFirstPrivate;
nSave[nThread][LastPrivate][j] = nLastPrivate;
nThreadPrivate = nThread;
nPrivate = nThread;
nShared = nThread;
nLastPrivate = nThread;
--nFirstPrivate;
}
}
}
for (i = 0 ; i < NUM_LOOPS ; ++i) {
for (j = 0 ; j < NUM_THREADS ; ++j) {
printf_s("These are the variables at entry of "
"loop %d of thread %d.\n", i + 1, j);
printf_s("nThreadPrivate = %d\n",
nSave[j][ThreadPrivate][i]);
printf_s(" nPrivate = %d\n",
nSave[j][Private][i]);
printf_s(" nFirstPrivate = %d\n",
nSave[j][FirstPrivate][i]);
printf_s(" nLastPrivate = %d\n",
nSave[j][LastPrivate][i]);
printf_s(" nShared = %d\n\n",
nSave[j][Shared][i]);
}
}
printf_s("These are the variables after exit from "
"the parallel region.\n");
printf_s("nThreadPrivate = %d (The last value in the "
"master thread)\n", nThreadPrivate);
printf_s(" nPrivate = %d (The value prior to "
"entering parallel region)\n", nPrivate);
printf_s(" nFirstPrivate = %d (The value prior to "
"entering parallel region)\n", nFirstPrivate);
printf_s(" nLastPrivate = %d (The value from the "
"last iteration of the loop)\n", nLastPrivate);
printf_s(" nShared = %d (The value assigned, "
"from the delayed thread, %d)\n\n",
nShared, SLEEP_THREAD);
}