template<typename T>
class ThreadPool
{public:ThreadPool(int threadnum = 8, int maxreqnum = 1000);~ThreadPool(){delete [] m_Pthread;m_Stop = true;}/* 往队列添加任务 */bool Append(T *request);/* 线程函数不能执行对象成员函数，所以声明为static，此时函数不能使用对象非静态成员，故将访问的工作交给Run函数，*   this 传递到args。（Work应该封装到类里面）——Singleton模式 */static void* Work(void *args);void Run(int index);private:/* 请求队列最大任务数 */int m_MaxRequestNum;/* 线程池线程数量 */int m_ThreadNum;pthread_t *m_Pthread;/* 线程是否应该结束 */bool m_Stop;/* 子线程在等待任务时，应该进入睡眠，用信号量；而资源竞争（获取队列中的一个任务）用互斥量保护 */pthread_mutex_t m_QueMutex;sem_t m_QueSem;/* 任务列表 */std::list<T *> m_WorkList;
};

创建并分离线程：

template<typename T>
ThreadPool<T>::ThreadPool(int threadnum, int maxreqnum): m_MaxRequestNum(maxreqnum), m_ThreadNum(threadnum), m_Pthread(nullptr), m_Stop(false)
{int ret;/* 信号量值小于零就block */ret = sem_init(&m_QueSem, 0, 0);if (ret == -1){printf("ThreadPool: [sem_init] failed, errno[%d]:%s\n", errno, strerror(errno));exit(-1);}m_QueMutex = PTHREAD_MUTEX_INITIALIZER;if (!m_Pthread){m_Pthread = (pthread_t *)malloc(sizeof(pthread_t) * m_ThreadNum);/* 如果分配失败，应该退出 */if (!m_Pthread){printf("ThreadPool: [malloc] failed, errno[%d]:%s\n", errno, strerror(errno));exit(-1);}}for (int i = 0; i < threadnum; ++i){/* 将this指针传递给static成员函数，实现Singleton模式 */ret = pthread_create(m_Pthread + i, nullptr, Work, this);if (ret != 0){delete [] m_Pthread;printf("ThreadPool: [pthread_create] failed, errno[%d]:%s\n", ret, strerror(ret));exit(-1);}/* 分离线程，子线程马上到执行区等待任务 */ret = pthread_detach(m_Pthread[i]);if (ret != 0){delete [] m_Pthread;printf("ThreadPool: [pthread_detach] failed, errno[%d]:%s\n", ret, strerror(ret));exit(-1);         }}
}

从任务列表获取任务，互斥量用于防止多个线程共同使用一个变量，而信号量避免的由于pthread_mutex_lock带来的cpu消耗，让线程进入睡眠状态：

template<typename T>
void* ThreadPool<T>::Work(void *args)
{static int index = 0;index++;ThreadPool<T> *pthreadpool = (ThreadPool<T> *)args;pthreadpool->Run(index);return nullptr;
}template<typename T>
void ThreadPool<T>::Run(int index)
{printf("pthread:%d\n", index);while (!m_Stop){sem_wait(&m_QueSem);printf("pthread:%d\n", index);pthread_mutex_lock(&m_QueMutex);if (m_WorkList.empty()){pthread_mutex_unlock(&m_QueMutex);continue;}/* 获取一个任务 */T* request = m_WorkList.front();m_WorkList.pop_front();pthread_mutex_unlock(&m_QueMutex);if (!request){continue;}request->Process();delete request;}
}

添加任务到任务列表，并发出有新任务到来的信号：

template<typename T>
bool ThreadPool<T>::Append(T *request)
{pthread_mutex_lock(&m_QueMutex);if (m_WorkList.size() > m_MaxRequestNum){pthread_mutex_unlock(&m_QueMutex);printf("ThreadPool: [Append] failed, Client sum is over m_MaxRequestNum \n");return false;}m_WorkList.push_back(request);pthread_mutex_unlock(&m_QueMutex);sem_post(&m_QueSem);return true;
}

源码见 Github: https://github.com/jammgit/ThreadPool