多线程编程实例---pthread_join函数详解1.doc

多线程编程实例-pthread_join函数详解1单处理器上的linux多线程，是通过分时操作完成的；此时互斥锁的作用，只有在时间足够的情况下才能体现出来，即有时线程内需要延时；否则只有第一个线程不断解锁和获锁，别的线程在第一个线程执行完前无法获得互斥锁。三 pthread_join pthread_exit函数pthread_join用来等待一个线程的结束。函数原型为：extern int pthread_join _P (pthread_t _th, void *_thread_return); 第一个参数为被等待的线程标识符，第二个参数为一个用户定义的指针，它可以用来存储被等待线程的返回值。这个函数是一个线程阻塞的函数，调用它的函数将 一直等待到被等待的线程结束为止，当函数返回时，被等待线程的资源被收回。一个线程的结束有两种途径，一种是象我们上面的例子一样，函数结束了，调用它的 线程也就结束了；另一种方式是通过函数pthread_exit来实现。它的函数原型为：extern void pthread_exit _P (void *_retval) _attribute_ (_noreturn_); 唯一的参数是函数的返回代码，只要pthread_join中的第二个参数thread_return不是NULL，这个值将被传递给 thread_return。最后要说明的是，一个线程不能被多个线程等待，否则第一个接收到信号的线程成功返回，其余调用pthread_join的线 程则返回错误代码ESRCH。在这一节里，我们编写了一个最简单的线程，并掌握了最常用的三个函数pthread_create，pthread_join和pthread_exit。下面，我们来了解线程的一些常用属性以及如何设置这些属性。 /源程序：/*thread_example.c : c multiple thread programming in linux */#include#include#include#include#define MAX1 10#define MAX2 30pthread_t thread2;pthread_mutex_t mut;int number=0, i;void *thread1() printf (thread1 : Im thread 1n); for (i = 0; i MAX1; i+) printf(thread1 : number = %d i=%dn,number,i); pthread_mutex_lock(&mut); number+; pthread_mutex_unlock(&mut); sleep(2); printf(thread1 :Is main function waiting for me acomplishing task? n); pthread_exit(NULL);void *thread2() printf(thread2 : Im thread 2n); for (i = 0; i MAX2; i+) printf(thread2 : number = %d i=%dn,number,i); pthread_mutex_lock(&mut); number+; pthread_mutex_unlock(&mut); sleep(3); printf(thread2 :Is main function waiting for me to acomplish task ?n); pthread_exit(NULL);void thread_create(void) int temp; memset(&thread, 0, sizeof(thread); /comment1 /*创建线程*/ if(temp = pthread_create(&thread0, NULL, thread1, NULL) != 0) /comment2 printf(线程1创建失败!n); else printf(Thread 1 is establishedn); if(temp = pthread_create(&thread1, NULL, thread2, NULL) != 0) /comment3 printf(线程2创建失败); else printf(Thread 2 is establishedn);void thread_wait(void) /*等待线程结束*/ if(thread0 !=0) /comment4 pthread_join(thread0,NULL); printf(Thread 1 is over n); if(thread1 !=0) /comment5 pthread_join(thread1,NULL); printf(Thread 2 is overn); int main() /*用默认属性初始化互斥锁*/ pthread_mutex_init(&mut,NULL); printf(I am the main funtion,and I am establishing threads. Ha-han); thread_create(); printf(I am the main funtion,and I am waiting for thread to accomplish task. Ha-han); thread_wait(); return 0;/执行情况1(linux终端)：rootlocalhost root# gcc -o joint joint.c -lpthreadrootlocalhost root# ./jointI am the main funtion,and I am establishing threads. Ha-hathread1 : Im thread 1thread1 : number = 0 i=0Thread 1 is establishedthread2 : Im thread 2thread2 : number = 1 i=0Thread 2 is establishedI am the main funtion,and I am waiting for thread to accomplish task. Ha-hathread1 : number = 2 i=1thread2 : number = 3 i=2thread1 : number = 4 i=3thread2 : number = 5 i=4thread1 : number = 6 i=5thread1 : number = 7 i=6thread2 : number = 8 i=7thread1 : number = 9 i=8thread2 : number = 10 i=9thread1 :Is main function waiting for me acomplishing task?Thread 1 is overthread2 : number = 11 i=11thread2 : number = 12 i=12thread2 : number = 13 i=13thread2 : number = 14 i=14thread2 : number = 15 i=15thread2 : number = 16 i=16thread2 : number = 17 i=17thread2 : number = 18 i=18thread2 : number = 19 i=19thread2 : number = 20 i=20thread2 : number = 21 i=21thread2 : number = 22 i=22thread2 : number = 23 i=23thread2 : number = 24 i=24thread2 : number = 25 i=25thre