Linux——互斥与同步练习
用多线程程序设计一个火车票售票系统,
要求至少有两个售票窗口,每个售票窗口
不能重复买票,将100张车票均匀的从两个
窗口卖出即可。
./a.out
窗口1 卖出车票 1
窗口2 卖出车票 2
窗口1 卖出车票 3
窗口2 卖出车票 4
.....
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <semaphore.h>
int num=100;
int WIN[2]={1,1};
sem_t sem_WIN;
pthread_mutex_t mutex;
pthread_mutex_t mutex_win;
int get_win()
{
sem_wait(&sem_WIN);
int i = 0 ;
for(i = 0 ;i<2;i++)
{
pthread_mutex_lock(&mutex_win);
if(1==WIN[i])
{
WIN[i] = 0 ;
pthread_mutex_unlock(&mutex_win);
return i;
}else
{
pthread_mutex_unlock(&mutex_win);
}
}
return -1;
}
void relese_win(int id)
{
pthread_mutex_lock(&mutex_win);
WIN[id]=1;
pthread_mutex_unlock(&mutex_win);
sem_post(&sem_WIN);
}
void* th(void* arg)
{
while(1)
{
pthread_mutex_lock(&mutex);
if(num>0)
{
int n = num--;
pthread_mutex_unlock(&mutex);
int id = get_win();
printf("win %d, ticket:%d tid:%lu\n",id+1 ,n,pthread_self());
usleep(1000*100);
relese_win(id);
}else
{
pthread_mutex_unlock(&mutex);
break;
}
}
return NULL;
}
int main(int argc, char *argv[])
{
pthread_t tid1,tid2;
pthread_mutex_init(&mutex,NULL);
pthread_mutex_init(&mutex_win,NULL);
sem_init(&sem_WIN,0,2);
pthread_create(&tid1,NULL,th,NULL);
pthread_create(&tid2,NULL,th,NULL);
pthread_join(tid1,NULL);
pthread_join(tid2,NULL);
sem_destroy(&sem_WIN);
pthread_mutex_destroy(&mutex);
pthread_mutex_destroy(&mutex_win);
return 0;
}
启动三个线程,th1输出a,th2输出b,th3输出c。输出
abcabcabcabc。 10个abc
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<pthread.h>
#include<string.h>
#include<semaphore.h>
sem_t sem1,sem2,sem3;
void *th1(void*arg)
{
int i=10;
while(i--)
{
sem_wait(&sem1);
printf("a");
fflush(stdout);
sem_post(&sem2);
}
return NULL;
}
void *th2(void *arg)
{
int i=10;
while(i--)
{
sem_wait(&sem2);
printf("b");
sleep(1);
fflush(stdout);
sem_post(&sem3);
}
return NULL;
}
void *th3(void *arg)
{
int i=10;
while(i--)
{
sem_wait(&sem3);
printf("c");
sleep(1);
fflush(stdout);
sem_post(&sem1);
}
return NULL;
}
int main(int argc, const char *argv[])
{
pthread_t tid1,tid2,tid3;
sem_init(&sem1,0,1);
sem_init(&sem2,0,0);
sem_init(&sem3,0,0);
pthread_create(&tid1,NULL,th1,NULL);
pthread_create(&tid2,NULL,th2,NULL);
pthread_create(&tid3,NULL,th3,NULL);
pthread_join(tid1,NULL);
pthread_join(tid2,NULL);
pthread_join(tid3,NULL);
sem_destroy(&sem1);
sem_destroy(&sem2);
sem_destroy(&sem3);
return 0;
}
原文地址:https://blog.csdn.net/m0_71703182/article/details/140117971
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