Simple pthread race condition in C++

pthread-race.cc

#include <pthread.h>

#include <cstdlib>
#include <iostream>

using namespace std;
int x = 0;

void *PrintHello(void *threadid) {
    long tid;
    tid = (long)threadid;
    x++;
    cout << "Hello World! Thread ID, " << tid << endl;
    pthread_exit(NULL);
}

pthread_t load_data_in_thread(long id) {
    pthread_t thread;
    void *arg = (void *)id;
    int rc = pthread_create(&thread, NULL, PrintHello, arg);
    if (rc) {
        cout << "Error:unable to create thread," << rc << endl;
        exit(-1);
    }
    return thread;
}

int main() {
    pthread_t thread1, thread2;

    cout << "main() : creating thread 1 " << endl;
    thread1 = load_data_in_thread(1);
    cout << "main() : creating thread 2 " << endl;
    thread2 = load_data_in_thread(2);
    pthread_join(thread1, 0);
    // pthread_join(thread2,0);
    cout << "Final value of x: " << x << endl;
}