C++ 线程池

#include <iostream>
#include <string>
#include <memory>
#include <vector>
#include <thread>
#include <queue>
#include <functional>
#include <mutex>
using namespace std;

class ThreadPool
{
public:
    ThreadPool(int numThreads) :m_Stop(false)
    {
        for (int i = 0; i != numThreads; ++i)
        {
            m_Threads.emplace_back([this]
                {
                    while (true)
                    {
                        std::unique_lock<std::mutex> lock(m_Mutex);
                        m_Condition.wait(lock, [this] { return !m_Tasks.empty() || m_Stop; });
                        if (m_Stop && m_Tasks.empty()) return;

                        std::function<void()> task(std::move(m_Tasks.front()));
                        m_Tasks.pop();
                        lock.unlock();
                        task();
                    }
                });
        }
    }
    ~ThreadPool()
    {
        {
            std::unique_lock<std::mutex> lock(m_Mutex);
            m_Stop = true;
        }
        m_Condition.notify_all();
        for (auto &t : m_Threads)
        {
            t.join();
        }
    }
    ThreadPool(ThreadPool &) = delete;
    ThreadPool &operator=(const ThreadPool &) = delete;
    template<class F, class... Args>
    void enQueue(F &&f, Args&&... args)
    {
        std::function<void()> task =
            std::bind(std::forward<F>(f), std::forward<Args>(args)...);
        {
            std::unique_lock<std::mutex> lock(m_Mutex);
            m_Tasks.emplace(std::move(task));
        }
        m_Condition.notify_all();
    }
private:
    std::vector<std::thread> m_Threads;
    std::queue<std::function<void()>> m_Tasks;
    std::mutex m_Mutex;
    std::condition_variable m_Condition;
    bool m_Stop;
};

int main()
{
    ThreadPool th_pool(4);
    for (int i = 0; i != 10; ++i)
    {
        th_pool.enQueue([i]
            {
                std::cout << "task : " << i << " is running " << '\n';
                std::this_thread::sleep_for(std::chrono::seconds(1));
                std::cout << "task : " << i << " is done " << '\n';
            });
    }

    system("pause");
    return EXIT_SUCCESS;
}

输出：

task : 0 is running
task : 1 is running
task : 2 is running
task : 3 is running
请按任意键继续. . . task : 0 is done
task : 4 is running
task : 2 is done
task : 5 is running
task : 1 is done
task : 6 is running
task : 3 is done
task : 7 is running
task : 4 is done
task : task : 85 is done
 is running
task : 6task : 9 is running  is done

task : 7 is done
task : 8 is done
task : 9 is done