#include <stdio.h>#include <errno.h>#include <unistd.h>#include <stdlib.h>#include <pthread.h>#define THREAD_MAX 4pthread_mutex_t mutex;pthread_t thread[THREAD_MAX];static int tries;static int started;void print_it(int *arg){pthread_t tid;tid = pthread_self();printf("Thread %lx was canceled on its %d try./n",tid,*arg);}void *Search_Num(int arg){pthread_t tid;int num;int k=0,h=0,j;int ntries;tid = pthread_self();/*while(pthread_mutex_trylock(&mutex) == EBUSY){printf("**************busy****************/n");pthread_testcancel();}*/srand(arg);num = rand()&0xFFFFFF;//pthread_mutex_unlock(&mutex);printf("thread num %lx/n",tid);ntries = 0;pthread_setcancelstate(PTHREAD_CANCEL_ENABLE,NULL);pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED,NULL);pthread_cleanup_push((void *)print_it,(void *)&ntries);while(1){num = (num+1)&0xffffff;ntries++;if(arg == num){//只允許一個線程操作此處while(pthread_mutex_trylock(&mutex) == EBUSY) { //一個線程操作后其余線程進入次循環掛起，等待pthread_cancel函數發送cancel信號終止線程k++;if(k == 10000){printf("----------2busy2-----------/n");}pthread_testcancel();}tries = ntries;//pthread_mutex_unlock(&mutex);  //如果加上這句話，將會有好幾個線程找到主函數中設定的值pidprintf("Thread %lx found the number!/n",tid);for(j = 0;j<THREAD_MAX;j++){if(thread[j]!=tid){pthread_cancel(thread[j]);}}break;}if(ntries%100 == 0){h++;/*線程阻塞，其他線程爭奪資源，或者是等待pthread_cancel函數發送cancel信號終止線程*/pthread_testcancel();/*這是為了弄明白pthread_testcancel函數的作用而設置的代碼段*/if(h == 10000){h = 0;printf("----------thread num %lx-------------/n",tid);}}}pthread_cleanup_pop(0);return (void *)0;}int main(){int i,pid;pid = getpid(); //設置要查找的數pthread_mutex_init(&mutex,NULL);printf("Search the num of %d/n",pid);for(started = 0; started < THREAD_MAX; started++){pthread_create(&thread[started],NULL,(void *)Search_Num,(void *)pid);}for(i = 0; i < THREAD_MAX; i++){printf("-----------i = %d--------------/n",i);pthread_join(thread[i],NULL);}printf("It took %d tries ot find the number!/n",tries);return 0;}

Search the num of 6531-----------i = 0--------------thread num b6fbcb70thread num b67bbb70thread num b5fbab70thread num b77bdb70----------thread num b67bbb70-------------Thread b67bbb70 found the number!----------thread num b6fbcb70-----------------------thread num b77bdb70-----------------------2busy2---------------------thread num b5fbab70-----------------------2busy2-----------Thread b5fbab70 was canceled on its 1174527 try.Thread b77bdb70 was canceled on its 1023100 try.-----------i = 1--------------Thread b6fbcb70 was canceled on its 1174527 try.-----------i = 2-------------------------i = 3--------------It took 1174527 tries ot find the number!