c多线程不加锁demo

//
// Created by gxf on 2019/12/13.
//
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

int shareInt = 0;
void increase_num(void);

int main() {
    int ret;
    pthread_t thread1, thread2, thread3;

    ret = pthread_create(&thread1, NULL, increase_num, NULL);
    ret = pthread_create(&thread2, NULL, increase_num, NULL);
    ret = pthread_create(&thread3, NULL, increase_num, NULL);

    pthread_join(thread1, NULL);
    pthread_join(thread2, NULL);
    pthread_join(thread3, NULL);

    printf("sharedInt:%d
", shareInt);

    return 0;
}

void increase_num(void) {
    long i, tmp;
    for (i=0; i <= 100000; i++) {
        tmp = shareInt;
        tmp = tmp + 1;
        shareInt = tmp;
    }
}