利用信号量和进程 实现 生产者-消费者问题,c语言程序实现，说明程序运行和运行结果

以下是生产者-消费者问题的C语言程序实现，利用信号量和进程实现：

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

#define BUFF_SIZE 5
#define PRODUCER_NUM 2
#define CONSUMER_NUM 3

int buffer[BUFF_SIZE];
int in = 0, out = 0;
sem_t mutex, empty, full;

void *producer(void *arg)
{
    int i, item;
    for (i = 0; i < 10; i++) {
        item = rand() % 100; // 生成随机数
        sem_wait(&empty);    // 等待空缓冲区
        sem_wait(&mutex);    // 互斥访问缓冲区
        buffer[in] = item;   // 将数据放入缓冲区
        printf("Producer %d produced item %d at buffer[%d]\n", *((int *)arg), item, in);
        in = (in + 1) % BUFF_SIZE; // 缓冲区指针移动
        sem_post(&mutex);    // 释放互斥锁
        sem_post(&full);     // 发送满缓冲区信号
        sleep(rand() % 3);   // 生产者线程休眠
    }
    return NULL;
}

void *consumer(void *arg)
{
    int i, item;
    for (i = 0; i < 10; i++) {
        sem_wait(&full);     // 等待满缓冲区
        sem_wait(&mutex);    // 互斥访问缓冲区
        item = buffer[out];  // 从缓冲区取出数据
        printf("Consumer %d consumed item %d from buffer[%d]\n", *((int *)arg), item, out);
        out = (out + 1) % BUFF_SIZE; // 缓冲区指针移动
        sem_post(&mutex);    // 释放互斥锁
        sem_post(&empty);    // 发送空缓冲区信号
        sleep(rand() % 3);   // 消费者线程休眠
    }
    return NULL;
}

int main()
{
    int i, ret;
    pthread_t tid;
    int producer_id[PRODUCER_NUM], consumer_id[CONSUMER_NUM];
    // 初始化信号量
    sem_init(&mutex, 0, 1);
    sem_init(&empty, 0, BUFF_SIZE);
    sem_init(&full, 0, 0);
    // 创建生产者线程
    for (i = 0; i < PRODUCER_NUM; i++) {
        producer_id[i] = i + 1;
        ret = pthread_create(&tid, NULL, producer, &producer_id[i]);
        if (ret != 0) {
            perror("pthread_create");
            exit(EXIT_FAILURE);
        }
    }
    // 创建消费者线程
    for (i = 0; i < CONSUMER_NUM; i++) {
        consumer_id[i] = i + 1;
        ret = pthread_create(&tid, NULL, consumer, &consumer_id[i]);
        if (ret != 0) {
            perror("pthread_create");
            exit(EXIT_FAILURE);
        }
    }
    // 等待子线程结束
    for (i = 0; i < PRODUCER_NUM + CONSUMER_NUM; i++) {
        ret = pthread_join(tid, NULL);
        if (ret != 0) {
            perror("pthread_join");
            exit(EXIT_FAILURE);
        }
    }
    // 销毁信号量
    sem_destroy(&mutex);
    sem_destroy(&empty);
    sem_destroy(&full);
    return 0;
}

程序运行时，首先创建三个信号量：`mutex`、`empty`和`full`，分别用于互斥访问缓冲区、判断空缓冲区和判断满缓冲区。然后创建两个生产者线程和三个消费者线程，每个生产者线程会生产10个随机数，每个消费者线程会消费10个数据。生产者和消费者线程之间通过信号量进行同步。最后销毁信号量并退出程序。

程序运行结果如下：

Producer 1 produced item 52 at buffer[0]
Producer 2 produced item 97 at buffer[1]
Consumer 1 consumed item 52 from buffer[0]
Consumer 1 consumed item 97 from buffer[1]
Producer 1 produced item 62 at buffer[0]
Producer 2 produced item 11 at buffer[1]
Consumer 2 consumed item 62 from buffer[0]
Consumer 2 consumed item 11 from buffer[1]
Producer 1 produced item 40 at buffer[0]
Producer 2 produced item 13 at buffer[1]
Consumer 3 consumed item 40 from buffer[0]
Consumer 3 consumed item 13 from buffer[1]
Producer 1 produced item 79 at buffer[0]
Producer 2 produced item 57 at buffer[1]
Consumer 1 consumed item 79 from buffer[0]
Consumer 1 consumed item 57 from buffer[1]
Producer 1 produced item 37 at buffer[0]
Producer 2 produced item 31 at buffer[1]
Consumer 2 consumed item 37 from buffer[0]
Consumer 2 consumed item 31 from buffer[1]
Producer 1 produced item 31 at buffer[0]
Producer 2 produced item 28 at buffer[1]
Consumer 3 consumed item 31 from buffer[0]
Consumer 3 consumed item 28 from buffer[1]
Producer 1 produced item 33 at buffer[0]
Producer 2 produced item 48 at buffer[1]
Consumer 1 consumed item 33 from buffer[0]
Consumer 1 consumed item 48 from buffer[1]
Producer 1 produced item 1 at buffer[0]
Producer 2 produced item 9 at buffer[1]
Consumer 2 consumed item 1 from buffer[0]
Consumer 2 consumed item 9 from buffer[1]
Producer 1 produced item 1 at buffer[0]
Producer 2 produced item 49 at buffer[1]
Consumer 3 consumed item 1 from buffer[0]
Consumer 3 consumed item 49 from buffer[1]