thread同步测试

1 编译运行附件中的代码，提交运行结果截图，并说明程序功能

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <semaphore.h>

#define NUM 5
int queue[NUM];
sem_t blank_number, product_number;

void *producer ( void * arg )
{
    static int p = 0;

    for ( ;; ) {
        sem_wait( &blank_number );
        queue[p] = rand() % 1000;
        printf("Product %d \n", queue[p]);
        p = (p+1) % NUM;
        sleep ( rand() % 5);
        sem_post( &product_number );
    }
}
void *consumer ( void * arg )
{

    static int c = 0;
    for( ;; ) {
        sem_wait( &product_number );
        printf("Consume %d\n", queue[c]);
        c = (c+1) % NUM;
        sleep( rand() % 5 );
        sem_post( &blank_number );
    }
}

int main(int argc, char *argv[] )
{
    pthread_t pid, cid;
    
    sem_init( &blank_number, 0, NUM );
    sem_init( &product_number, 0, 0);
    pthread_create( &pid, NULL, producer, NULL);
    pthread_create( &cid, NULL, consumer, NULL);
    pthread_join( pid, NULL );
    pthread_join( cid, NULL );
    sem_destroy( &blank_number );
    sem_destroy( &product_number );
    return 0;
}

结果

改进

模计算

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <semaphore.h>
#include <unistd.h>
#define NUM 4
int queue[NUM];
sem_t blank_number, product_number,mutex;
 
int c = 0;
 
void *producer ( void * arg )//生产者
{
    static int p = 0;
 
    for ( ;; ) {
        sem_wait( &blank_number );//空格子锁
        queue[p] = rand() % 1000;
        printf("Product %d \n", queue[p]);
        p = (p+1) % NUM;
        sleep ( rand() % 5);
        sem_post( &product_number );
    }
}
void *consumer ( void * arg )//消费者
{
 
    for( ;; ) {
        sem_wait(&mutex);
        sem_wait( &product_number );
        printf("Consume %d\n", queue[c]);
        c = (c+1) % NUM;
        sleep( rand() % 5 );
        sem_post( &blank_number );
        sem_post( &mutex);
    }
}
 
int main(int argc, char *argv[] )
{
    pthread_t pid, cid,cid1,cid2,cid3,cid4,cid5;
     
    sem_init( &blank_number, 0, NUM );//初始化空格信号量
    sem_init( &product_number, 0, 0);//初始化产品信号量
    sem_init( &mutex, 1, 1);//初始化（消费者的）互斥信号量为1
    pthread_create( &pid, NULL, producer, NULL);//创建生产者线程
    pthread_create( &cid, NULL, consumer, NULL);//创建消费者线程
    pthread_create( &cid1, NULL, consumer, NULL);//创建消费者线程
    pthread_create( &cid2, NULL, consumer, NULL);//创建消费者线程
    pthread_create( &cid3, NULL, consumer, NULL);//创建消费者线程
    pthread_create( &cid4, NULL, consumer, NULL);//创建消费者线程
     pthread_create( &cid5, NULL, consumer, NULL);//创建消费者线程
    
    pthread_join( pid, NULL );//等待生产者线程执行完
    pthread_join( cid, NULL );//等待消费者线程执行完
    pthread_join( cid1, NULL );//等待消费者线程执行完
    pthread_join( cid2, NULL );//等待消费者线程执行完
    pthread_join( cid3, NULL );//等待消费者线程执行完
    pthread_join( cid4, NULL );//等待消费者线程执行完
    pthread_join( cid5, NULL );//等待消费者线程执行完
 
    sem_destroy( &blank_number );
    sem_destroy( &product_number );
    return 0;
}

结果