std::this_thread::get_id - cppreference.com

#include <chrono>
#include <iostream>
#include <syncstream>
#include <thread>
using namespace std::chrono_literals;

void foo()
{
    std::thread::id this_id = std::this_thread::get_id();
 
    std::osyncstream(std::cout) << "线程 " << this_id << " 睡眠...\n";

    std::this_thread::sleep_for(500ms);
}

int main()
{
    std::jthread t1{foo};
    std::jthread t2{foo};
}

线程 140113018054400 睡眠...
线程 140113009661696 睡眠...