多线程中使用mktime和setenv函数

淡淡的烟草味﹌ 2022-08-01 13:56 177阅读 0赞

在编写ATS插件的过程中,发现使用mktime会偶尔出现段错误, 经过网上调研,发现mktime等函数不是线程安全的, 于是编写下面的代码进行测试.

注意加锁和不加锁区别很大, 在mktime中使用多线程, 加上互斥锁就没有问题.

//gcc -g mktime_multithread.c -o mktime_multithread -lpthread -std=c99
    //
    #include <stdlib.h>
    #include <stdio.h>
    #include <string.h>
    #include <time.h>
    #include <unistd.h>
    #include <pthread.h>
    
    pthread_mutex_t mutex;
    
    void* test_setenv(void *arg)
    {
        char ac_name[1024] = {};
        for (int i = 0; i < 10000; i++)
        {
            snprintf(ac_name, sizeof(ac_name), "stra_1_fe_filter_dt_other_hadoop_arg_%d", i);
            printf("setenv %s\n",ac_name);
            pthread_mutex_lock(&mutex);
            setenv(ac_name," 1500",0);
            pthread_mutex_unlock(&mutex);
        }
        return NULL;
    }
    
    void* test_mktime(void* arg){
        for (int i = 0; i < 10000; i++)
        {
            /*测试非法日期会不会导致程序异常*/
            struct tm st_tm;
            memset(&st_tm,0,sizeof(st_tm));
            strptime("201506270828001","%Y%m%d%H%M",&st_tm);
            pthread_mutex_lock(&mutex);
            time_t st_time = mktime(&st_tm);
            pthread_mutex_unlock(&mutex);
            printf("time_t=%lu\n",st_time);
        }
        return NULL;
    }
    
    int main(int argc, char* argv[])
    {
        pthread_mutex_init(&mutex,NULL);
    
        pthread_t pt[2] = {0};
        pthread_create(&pt[0], NULL, test_setenv, NULL);
        pthread_create(&pt[1], NULL, test_mktime, NULL);
    
        pthread_join(pt[0], NULL);
        pthread_join(pt[1], NULL);
    
        pthread_mutex_destroy(&mutex);
    
        return 0;
    }

参考文献

\[1\].http://www.xuebuyuan.com/1824402.html