//信号量---线程间通信//“生产者消费者” 问题#include<stdio.h>#include<stdlib.h>#include<unistd.h>#include<semaphore.h>#include<pthread.h>#define msleep(x)   usleep(x*1000)#define PRODUCT_SPEED       3               //生产速度#define CONSUM_SPEED        1               //消费速度#define INIT_NUM                3               //仓库原有产品数#define TOTAL_NUM               10          //仓库容量 sem_t p_sem, c_sem, sh_sem;int num=INIT_NUM; void product(void)                          //生产产品{    sleep(PRODUCT_SPEED);} int add_to_lib()                                //添加产品到仓库{    num++;//仓库中的产品增加一个    msleep(500);    return num;} void consum()                                       //消费{    sleep(CONSUM_SPEED);} int sub_from_lib()                          //从仓库中取出产品{    num--; //仓库中的产品数量减一    msleep(500);    return num;} void *productor(void *arg)          //生产者线程{    while(1)    {        sem_wait(&p_sem);//生产信号量减一        product();// 生产延时               sem_wait(&sh_sem);//这个信号量是用来互斥的        printf("push into! tatol_num=%d\n",add_to_lib());        sem_post(&sh_sem);          sem_post(&c_sem);  //消费信号量加一    }} void *consumer(void *arg)               //消费者线程{    while(1)    {                 sem_wait(&c_sem); //消费者信号量减一            sem_wait(&sh_sem);        printf("pop out! tatol_num=%d\n",sub_from_lib());        sem_post(&sh_sem);              sem_post(&p_sem);//生产者信号量加一         consum();//消费延时                               }} int main(){    pthread_t tid1,tid2;    sem_init(&p_sem,0,TOTAL_NUM-INIT_NUM);         sem_init(&c_sem,0,INIT_NUM);         sem_init(&sh_sem,0,1);         pthread_create(&tid1,NULL,productor,NULL);    pthread_create(&tid2,NULL,consumer,NULL);         pthread_join(tid1,NULL);    pthread_join(tid2,NULL);    return 0;}http://www.cnblogs.com/hnrainll/archive/2011/04/21/2024089.html