ThreadPrograming

#include <stdio.h>
#include <stdlib.h>//for exit() #include <pthread.h>//for pthread()
#include <unistd.h> //for fork()and execl() #include <sys/types.h>
#include <semaphore.h>//for sem_wait()and sem_post()

int n=10,in=0,out=0,buffer[10]; //global variables:buffer sem_t defines signal and two signal inited in main //n用作取模，in和out分别当作生产者的放和消费者的取,buffer[10]代表十个缓冲区，可同时读和写 sem_t empty,full; //当库存为空时，消费者不再拿。当库存为满时，生产者不再生产。

void* producer(voidarg) { int tag=pthread_self()%100; //线程id的模，可重复 int nextPro; //用作输出当前线程产品名 srand(time(NULL)+tag); //pthread_self(): thread number Srand: rand seed; // one producer produces constantly while(1) { nextPro=rand()%97; sem_wait(&empty); buffer[in]=nextPro; printf("production:%d %d\n",nextPro,buffer[in]); //buffer[in]可能在多线程中发生冲突而改变 usleep(10001000/20); //sleep: unit is weimiao; 1 seconds = 10001000 weimiao,except 20 equal to 0.05 seconds; in=(in+1)%n; sem_post(&full); //wait and signal of signmount usleep(10001000/2); } } //consumer process void* consumer(void arg) { int item; while(1) { sem_wait(&full); item = buffer[out]; sem_post(&empty); printf("consume:%d\n",buffer[out]); out=(out+1)%n; usleep(10001000/2); } }

int main() { pthread_t tid[2]; //初始有10个缓冲区 //线程号数组：根据需要，有多少线程，就定位多大 sem_init(&empty,0,10); //整形信号量初始化函数：第3个参数表示信号量的初始值，第2个参数可暂时不管 sem_init(&full,0,0); pthread_create(&tid[0],NULL,producer,NULL); //create thread pthread_create(&tid[1],NULL,consumer,NULL); for(int i=0;i<2;i++) { pthread_join(tid[i],NULL); //等待所有线程结束，若不然，main结束后其他线程将被终止 } printf("main is over\n"); }