openmp中的数据共享

Question

在编写多线程程序时，默认是所有线程之间的数据共享内存，并且需要指定私有内容。是否可以将所有数据声明为私有？

此致 -Mohd

Answer 1

您可能希望查看thread local storage。

Answer 2

你可以，for example：

#include <omp.h>
#include <stdio.h>
#include <stdlib.h>

int main (int argc, char *argv[]) 
{
int nthreads, tid;

/* Fork a team of threads giving them their own copies of variables */
#pragma omp parallel private(nthreads, tid)
  {

  /* Obtain thread number */
  tid = omp_get_thread_num();
  printf("Hello World from thread = %d\n", tid);

  /* Only master thread does this */
  if (tid == 0) 
    {
    nthreads = omp_get_num_threads();
    printf("Number of threads = %d\n", nthreads);
    }

  }  /* All threads join master thread and disband */

}

但是，您无法使用异步消息替换共享数据，因为无法保证openmp任务不会异常运行：

Use Threads Correctly = Isolation + Asynchronous Messages