C++ 线程池核心原理与代码实现

ThreadPool.cpp

#include "ThreadPool.h"

ThreadPool::ThreadPool(size_t n)  
    : m_stop(false)  
{  
    for (size_t i = 0; i < n; ++i)  
    {  
        m_workers.emplace_back([this] {  
            while (true)  
            {  
                Task task;  
                {  
                    std::unique_lock<std::mutex> lock(m_mutex);  
                    m_cond.wait(lock, [this] {  
                        return m_stop || !m_tasks.empty();  
                    });

                    if (m_stop && m_tasks.empty())  
                        return;

                    task = std::move(m_tasks.front());  
                    m_tasks.pop();  
                }  
                task();  
            }  
        });  
    }  
}

ThreadPool::~ThreadPool()  
{  
    {  
        std::unique_lock<std::mutex> lock(m_mutex);  
        m_stop = true;  
    }  
    m_cond.notify_all();

    for (auto& t : m_workers)  
        t.join();  
}

void ThreadPool::Push(Task task)  
{  
    {  
        std::unique_lock<std::mutex> lock(m_mutex);  
        m_tasks.push(std::move(task));  
    }  
    m_cond.notify_one();  
}

4. 基础用法示例

int main()  
{  
    ThreadPool pool(3);  // 3 个工作线程

    for (int i = 0; i < 10; ++i)  
    {  
        pool.Push([i] {  
            printf("task %d running in thread %ld\n",  
                   i, std::this_thread::get_id());  
            std::this_thread::sleep_for(std::chrono::seconds(1));  
        });  
    }

    getchar();  
    return 0;  
}

5. Makefile 构建配置

CXX := g++  
CXXFLAGS := -std=c++11 -Wall -O2 -pthread

TARGET := threadpool_demo

SRCS := \  
            main.cpp \  
                  ThreadPool.cpp

OBJS := $(SRCS:.cpp=.o)

all: $(TARGET)

$(TARGET): $(OBJS)  
            $(CXX) $(CXXFLAGS) -o $@ $^

%.o: %.cpp  
            $(CXX) $(CXXFLAGS) -c $< -o $@

clean:  
    rm -f $(OBJS) $(TARGET)

.PHONY: all clean

执行结果如下：

text
./threadpool_demo
task 0 running in thread 140640437704448  
task 1 running in thread 140640446097152  
task 2 running in thread 140640429311744  
task 3 running in thread 140640437704448  
task 4 running in thread 140640446097152  
task 5 running in thread 140640429311744  
task 6 running in thread 140640446097152  
task 8 running in thread 140640429311744  
task 7 running in thread 140640437704448  
task 9 running in thread 140640446097152