how can i run these two proceses normally in c language?

this code works fine but consumer process does not work, i tried to get producer_pid value and check what is going on but when i write the printf("%d\n",producer_pid) it gives two values when do not put \n it gives one value. i am new to all computer programming i am educating myself, if the question is so bad i am sorry

i think producer process is not ending any idea that could help me?

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

#define BUFFER_SIZE 2

int buffer[BUFFER_SIZE];
int sayac = 0;

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

void produce(int item) {
    buffer[sayac] = item;
    sayac++;
}

int consume() {
    int item = buffer[sayac - 1];
    sayac--;
    return item;
}

void *producer_thread(void *arg) {
    int *pipe_fd = (int *)arg;

    for (int i = 1; i <= 10; i++) {
        pthread_mutex_lock(&mutex);
        while (sayac == BUFFER_SIZE) {
            pthread_mutex_unlock(&mutex);
            usleep(100000);  // Kısa bir süre bekleyerek döngüyü serbest bırak
            pthread_mutex_lock(&mutex);
        }

        produce(i);
        printf("Üretici: %d üretildi.\n", i);

        write(pipe_fd[1], &i, sizeof(i));

        pthread_mutex_unlock(&mutex);
        sleep(1);
    }
    close(pipe_fd[1]);
    return NULL;
}

void *consumer_thread(void *arg) {
    int *pipe_fd = (int *)arg;

    for (int i = 1; i <= 10; i++) {
        pthread_mutex_lock(&mutex);
        while (sayac == 0) {
            pthread_mutex_unlock(&mutex);
            usleep(100000);  // Kısa bir süre bekleyerek döngüyü serbest bırak
            pthread_mutex_lock(&mutex);
        }

        int item = consume();
        printf("Tüketici: %d tüketildi.\n", item);

        int received_data;
        read(pipe_fd[0], &received_data, sizeof(received_data));

        pthread_mutex_unlock(&mutex);
        sleep(1);
    }
    close(pipe_fd[0]);
    return NULL;
}

int main() {
    int pipe_fd[2];
    if (pipe(pipe_fd) == -1) {
        perror("Pipe oluşturulamadı");
        return 1;
    }

    pid_t producer_pid = fork();
    printf("%d ---------------",producer_pid);

    if (producer_pid == 0) {
        // Yavru üretici işlem kodu
        close(pipe_fd[0]); // Okuma tarafını kapat
        producer_thread((void *)pipe_fd);
        exit(0);
    } else if (producer_pid > 0) {
        pid_t consumer_pid = fork();

        if (consumer_pid == 0) {
            // Yavru tüketici işlem kodu
            close(pipe_fd[1]); // Yazma tarafını kapat
            consumer_thread((void *)pipe_fd);
            exit(0);
        } else if (consumer_pid > 0) {
            // Ana işlem kodu
            close(pipe_fd[0]); // Okuma tarafını kapat
            close(pipe_fd[1]); // Yazma tarafını kapat

            wait(NULL);
            wait(NULL);

            printf("Ana işlem tamamlandı.\n");
        } else {
            fprintf(stderr, "Tüketici işlem oluşturulamadı.\n");
            return 1;
        }
    } else {
        fprintf(stderr, "Üretici işlem oluşturulamadı.\n");
        return 1;
    }

    return 0;
}

>Solution :

the main problem here is that you’re opening a pthread mutex to sync between processes opened using fork().

pthread_mutex, as its name would suggest, is designed to sync between threads.
It will not be able to sync between processes created using fork since the processes will have a different memory space.

For your implementation, there isn’t much of a point to even use pthread_mutex. write() and read() are blocking, so you can have both processes sync by using the pipe.

On a different subject, when you use printf(), sometimes the OS will wait and not print all of the log. use fflush() to see all your logs.