linux 线程pv操作

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

#define NUM_THREADS 5

sem_t sem;

void* thread_func(void* arg) {
    int thread_id = *(int*)arg;
    
    // P操作：等待信号量
    sem_wait(&sem);
    
    printf("Thread %d is accessing the shared resource.
", thread_id);
    sleep(1); // 模拟访问共享资源的时间
    
    printf("Thread %d is done accessing the shared resource.
", thread_id);
    
    // V操作：释放信号量
    sem_post(&sem);
    
    return NULL;
}

int main() {
    pthread_t threads[NUM_THREADS];
    int thread_ids[NUM_THREADS];
    
    // 初始化信号量，初始值为1
    sem_init(&sem, 0, 1);
    
    // 创建线程
    for (int i = 0; i < NUM_THREADS; i++) {
        thread_ids[i] = i;
        pthread_create(&threads[i], NULL, thread_func, &thread_ids[i]);
    }
    
    // 等待线程结束
    for (int i = 0; i < NUM_THREADS; i++) {
        pthread_join(threads[i], NULL);
    }
    
    // 销毁信号量
    sem_destroy(&sem);
    
    return 0;
}