線程 Joining and Detaching相關函數4個
pthread_joinpthread_detach
pthread_attr_setdetachstate
pthread_attr_getdetachstate
Joining的作用
Joining是線程同步的方法之一
當且僅當線程被設置為joinable時其可被Joining
一個例子:
#include <pthread/pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define NUM_THREADS 4
void *BusyWork(void *t)
{
int i;
long tid;
double result=0.0;
tid = (long)t;
printf("Thread %ld starting
\n",tid);
for (i=0; i<1000000; i++)
{
result = result + sin(i) * tan(i);
}
printf("Thread %ld done. Result = %e\n",tid, result);
pthread_exit((void*) t);
}
int main (int argc, char *argv[])
{
pthread_t thread[NUM_THREADS];
pthread_attr_t attr;
int rc;
long t;
void *status;
//! 設置線程屬性
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
for(t=0; t<NUM_THREADS; t++)
{
printf("Main: creating thread %ld\n", t);
rc = pthread_create(&thread[t], &attr, BusyWork, (void *)t);
if (rc)
{
printf("ERROR; return code from pthread_create()is %d\n", rc);
exit(-1);
}
}
//! 銷毀線程屬性
pthread_attr_destroy(&attr);
for(t=0; t<NUM_THREADS; t++)
{
rc = pthread_join(thread[t], &status);
if (rc)
{
printf("ERROR; return code from pthread_join()is %d\n", rc);
exit(-1);
}
printf("Main: completed join with thread %ld having a status of %ld\n",t,(long)status);
}
printf("Main: program completed. Exiting.\n");
pthread_exit(NULL);
}