std::thread t(hello);
//t.join();
t.detach();

detach  join  启动线程
join    阻塞调用线程，等待被调线程执行完成
detach  不阻塞 




#include "iostream"
#include "thread"
#include "chrono"

using namespace std;

void hello(){
    while(true){
        this_thread::sleep_for(chrono::seconds(1));
        cout << this_thread::get_id() << " hello" << endl;
    }
  
}

int main(){

  std::thread t(hello);
  //t.join();
  t.detach();
  
  while(true){
        this_thread::sleep_for(chrono::seconds(2));
        cout << this_thread::get_id() << " main hello" << endl;
  }
  
  return 0;
}