c++ - 为什么我得到 "error: ‘pthread_delay_np’ was not declared in this scope”？

Question

我试图看看是否有可能避免线程在 thread_create 之后立即启动。所以，我遇到了 pthread_delay_np 并尝试了这个例子:

#define _MULTI_THREADED
#include <stdio.h>
#include <time.h>
#include <pthread.h>
#define NTHREADS 5

void *threadfunc(void *parm)
{
  int               rc;
  struct timespec   ts = {0, 0};

  /* 5 and 1/2 seconds */
  ts.tv_sec  = 5;
  ts.tv_nsec = 500000000;

  printf("Thread blocked\n");
  rc = pthread_delay_np(&ts);
  if (rc != 0) {
    printf("pthread_delay_np() - return code %d\n", rc);
    return (void*)&rc;
  }
  printf("Wait timed out!\n");

  return NULL;
}

int main(int argc, char **argv)
{
  int                   rc=0;
  int                   i;
  pthread_t             threadid[NTHREADS];
  void                 *status;
  int                   fail=0;

  printf("Enter Testcase - %s\n", argv[0]);

  printf("Create %d threads\n", NTHREADS);
  for(i=0; i<NTHREADS; ++i) {
    rc = pthread_create(&threadid[i], NULL, threadfunc, NULL);
  }

  printf("Wait for threads and cleanup\n");
  for (i=0; i<NTHREADS; ++i) {
    rc = pthread_join(threadid[i], &status);
    if (status != NULL) {
      fail = 1;
    }
  }

  if (fail) {
    printf("At least one thread failed!\n");
    return 1;
  }
  printf("Main completed\n");
  return 0;
}

但我不断收到“错误:‘pthread_delay_np’未在此范围内声明”。有人知道为什么吗？

此外，是否有任何其他方法可以防止线程在 thread_create 之后立即启动？与调度程序有关吗？

提前致谢!

Answer 1

引自some mailing list :

It is also available on HP-UX, VMS and Tru64 UNIX. pthread_delay_np() originated in the D4 draft of the POSIX.1c standard. The main implementer of POSIX.1c D4 was OSF for Distributed Computing Environment (DCE). The suffix _np denotes that the API is non-portable and cannot be relied on to be available on another platform. Generally nanosleep() is what you want to use as a replacement.