printf and Concurrency

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

pthread_mutex_t mutex;
void mutex_init(){
	int res = pthread_mutex_init(&mutex, NULL);
	if (res == 0) {
		printf("Mutex lock initialized successfully!\n");
	} else {
		printf("Failed to initialize mutex lock. Error code: %d\n", res);
	}
	return;
}
pthread_cond_t cond;
void cv_init(){
    int res;
    res = pthread_cond_init(&cond, NULL);
    if (res == 0) {
        printf("Condition variable initialized successfully!\n");
    } else {
        printf("Failed to initialize condition variable. Error code: %d\n", res);
    }
    return;
}
int condition = 0; // Explicitly initialize the condition variable to 0
void *thread_func(void *arg) {
	printf("Thread %ld is requiring lock.\n", (long)pthread_self());
    pthread_mutex_lock(&mutex);
    while (!condition) {
        pthread_cond_wait(&cond, &mutex);
        // The thread will block here, and the mutex lock will be released until the condition variable is signaled.
    }
    printf("Thread %ld continues\n", (long)pthread_self());
    pthread_mutex_unlock(&mutex);
    return NULL;
}

int main() {
	mutex_init();
	cv_init();
    pthread_t threads[8];
    for (int i = 0; i < 8; i++) {
        pthread_create(&threads[i], NULL, thread_func, NULL);
    }
    
	usleep(100000); // Sleep for a second to ensure the thread is waiting on the condition variable
    printf("Main thread is about to signal the condition variable.\n");
    pthread_mutex_lock(&mutex);
    condition = 1;
    printf("Condition fulfilled by main thread.\n");
    for(int i = 0; i < 8; i++){
	    pthread_cond_signal(&cond);
    }
    pthread_mutex_unlock(&mutex);

    for (int i = 0; i < 8; i++) {
        pthread_join(threads[i], NULL);
    }
    
    // Destroy the condition variable and mutex to release resources
    pthread_cond_destroy(&cond);
    pthread_mutex_destroy(&mutex);

    return 0;
}

==87816== ERROR SUMMARY: 286 errors from 4 contexts (suppressed: 198 from 44)

void *thread_func(void *arg) {
	// printf("Thread %ld is requiring lock.\n", (long)pthread_self());
    pthread_mutex_lock(&mutex);
    while (!condition) {
        pthread_cond_wait(&cond, &mutex);
        // The thread will block here, and the mutex lock will be released until the condition variable is signaled.
    }
    printf("Thread %ld continues\n", (long)pthread_self());
    pthread_mutex_unlock(&mutex);
    return NULL;
}

int printf(const char *restrict format, ...){
    flockfile(stdout); // Lock
    // Write buffer
	// Flushing the buffer
	funlockfile(stdout); // Unlock
}