在多线程环境中使用localtime存在安全隐患

    #include<fstream>
    #include<iostream>
    #include <map>
    #include <unistd.h>
    using namespace std;
    
    void*  Fun1(void *arg){
    struct tm * tm= (struct tm*)arg;
    tm->tm_mday = tm->tm_mday+1;
    tm->tm_hour = 8;
    tm->tm_min = 0;
    tm->tm_sec = 0;
    usleep(500);
    cout<<mktime(tm)<<endl; //1588240800  2020-04-30 18:00:00
    }
    void*  Fun2(void *arg){
    struct tm * tm= (struct tm*)arg;
    tm->tm_mday = tm->tm_mday+1;
    tm->tm_hour = 18;
    tm->tm_min = 0;
    tm->tm_sec = 0;
    cout<<mktime(tm)<<endl;//1588240800   2020-04-30 18:00:00
    }