采用有序分配法预防死锁的哲学家就餐问题c语言代码

以下是一个使用有序分配法预防死锁的哲学家就餐问题的C语言代码：

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

#define NUM_PHILOSOPHERS 5

pthread_mutex_t forks[NUM_PHILOSOPHERS];
pthread_t philosophers[NUM_PHILOSOPHERS];

void *philosopher(void *id) {
    int philosopher_id = *(int*)id;
    int left_fork = philosopher_id;
    int right_fork = (philosopher_id + 1) % NUM_PHILOSOPHERS;

    while (1) {
        // Pick up left fork
        pthread_mutex_lock(&forks[left_fork]);

        // Pick up right fork
        if (pthread_mutex_trylock(&forks[right_fork]) == 0) {
            // Eat
            printf("Philosopher %d is eating\n", philosopher_id);
            usleep(rand() % 1000000);

            // Put down right fork
            pthread_mutex_unlock(&forks[right_fork]);
        }

        // Put down left fork
        pthread_mutex_unlock(&forks[left_fork]);

        // Think
        printf("Philosopher %d is thinking\n", philosopher_id);
        usleep(rand() % 1000000);
    }
}

int main() {
    int i;

    // Initialize mutexes
    for (i = 0; i < NUM_PHILOSOPHERS; i++) {
        pthread_mutex_init(&forks[i], NULL);
    }

    // Create philosophers
    for (i = 0; i < NUM_PHILOSOPHERS; i++) {
        int *id = malloc(sizeof(int));
        *id = i;
        pthread_create(&philosophers[i], NULL, philosopher, id);
    }

    // Wait for philosophers to finish
    for (i = 0; i < NUM_PHILOSOPHERS; i++) {
        pthread_join(philosophers[i], NULL);
    }

    // Destroy mutexes
    for (i = 0; i < NUM_PHILOSOPHERS; i++) {
        pthread_mutex_destroy(&forks[i]);
    }

    return 0;
}

在这个实现中，每个哲学家都首先尝试拿起左边的叉子，然后尝试拿起右边的叉子。如果右边的叉子已经被别的哲学家拿起来了，那么这个哲学家就会放下左边的叉子，继续思考。这样可以保证每个哲学家至少能拿到一支叉子，从而避免死锁的发生。