Thread-ID 在我的 boost::asio::thread_pool 中始终相同

Question

我尝试了 boost docs 中的示例：

#include <boost/thread/thread.hpp>
#include <iostream>
#include <boost/asio/post.hpp>
#include <boost/asio/thread_pool.hpp>

int count = 0;

void my_task() {
    count++;
    const auto my_count = count;
    std::cout << "Task " << my_count << ") BEGIN: Thread-ID:" << boost::this_thread::get_id << std::endl;
    boost::this_thread::sleep(1000000000);
    std::cout << "Task " << my_count << ") END:   Thread-ID:" << boost::this_thread::get_id << std::endl;
    
}

int main(int argc, char** argv) {

    std::cout << "Main-thread-ID:  " << boost::this_thread::get_id << std::endl;
    
    // Launch the pool with two threads.
    boost::asio::thread_pool pool(2);

    // Submit a function to the pool.
    boost::asio::post(pool, my_task);
    boost::asio::post(pool, my_task);
    boost::asio::post(pool, my_task);
    boost::asio::post(pool, my_task);
    boost::asio::post(pool, my_task);

    // Wait for all tasks in the pool to complete.
    pool.join();

    return 0;
}

输出为：

Main-thread-ID:  00CC96C6
Task 1) BEGIN: Thread-ID:00CC96C6
Task 2) BEGIN: Thread-ID:00CC96C6
Task 1) END:   Thread-ID:00CC96C6
Task 3) BEGIN: Thread-ID:00CC96C6
Task 2) END:   Thread-ID:00CC96C6
Task 4) BEGIN: Thread-ID:00CC96C6
Task 4) END:   Thread-ID:00CC96C6
Task 3) END:   Thread-ID:00CC96C6
Task 5) BEGIN: Thread-ID:00CC96C6
Task 5) END:   Thread-ID:00CC96C6

为什么一直出现同一个线程ID？我做错了什么吗？它仍然并行执行我的任务。所以，我不太担心。

当我尝试 similiar example 和 boost::thread_group 时，我看到了相同的行为。

Answer 1

谢谢！我将所有出现的 boost::this_thread::get_id 更改为 boost::this_thread::get_id()，这导致了不同线程 ID 的预期输出：

Main-thread-ID:  5a78
Task 1) BEGIN: Thread-ID:77d0
Task 1) BEGIN: Thread-ID:5f34
Task 1) END:   Thread-ID:5f34
Task 1) END:   Thread-ID:77d0
Task 2) BEGIN: Thread-ID:5f34
Task 3) BEGIN: Thread-ID:77d0
Task Task 2) END:   Thread-ID:5f34
3) END:   Thread-ID:77d0
Task 4) BEGIN: Thread-ID:77d0
Task 4) END:   Thread-ID:77d0

Thread-ID 在我的 boost::asio::thread_pool 中始终相同

Thread-ID is always the same in my boost::asio::thread_pool

c++

multithreading

boost

boost-thread

boost-asio