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一、C++实现线程池

1. 头文件

#define _CRT_SECURE_NO_WARNINGS
#pragma once
#include<iostream>
#include<string.h>
#include<string>
#include<pthread.h>
#include<stdlib.h>
#include<queue>
#include<unistd.h>
using namespace std;using callback = void(*)(void*);
//任务的结构体
template<typename T>
struct Task
{Task(){function = nullptr;args = nullptr;}Task(callback fun, void* args){function = fun;this -> args = (T*)args;}callback function;T* args;
};//任务队列
template<typename T>
class TaskQueue
{
public:TaskQueue(){pthread_mutex_init(&mutex,NULL);}~TaskQueue(){pthread_mutex_destroy(&mutex);}//添加任务void AddTask(Task<T> task){pthread_mutex_lock(&mutex);queue.push(task);pthread_mutex_unlock(&mutex);}void AddTask(callback fun, void* args){pthread_mutex_lock(&mutex);Task<T> task(fun,args); queue.push(task);pthread_mutex_unlock(&mutex);}//取出一个任务Task<T> TakeTask(){Task<T> task;pthread_mutex_lock(&mutex);if (queue.size() > 0){task = queue.front();queue.pop();}pthread_mutex_unlock(&mutex);return task;}//获取当前队列中的任务个数inline int GetTaskNum(){return queue.size();}
private:pthread_mutex_t mutex; //互斥锁std::queue<Task<T>> queue;
};//线程池
template<typename T>
class ThreadPool
{
public:ThreadPool(int min , int max){//实例化任务队列taskqueue = new TaskQueue<T>;//初始化线程池min_num = min;max_num = max;busy_num = 0;live_num = min;//根据线程最大上限,给线程数组分配内存threadID = new pthread_t[max];if (threadID == nullptr){cout << "new threadID fail" << endl;}//初始化线程IDmemset(threadID, 0, sizeof(pthread_t) * max);//初始化互斥锁和条件变量if (pthread_mutex_init(&mutex_pool, NULL) != 0 ||pthread_cond_init(&notempty, NULL) != 0){cout << "mutex or cond init fail" << endl;}//创建线程for (size_t i = 0; i < min; ++i){pthread_create(&threadID[i], NULL, Work, this);cout << "create thread ID :" << to_string(threadID[i]) << endl;}pthread_create(&managerID, NULL, Manage, this);}~ThreadPool(){shutdown = true;//销毁管理者进程pthread_join(managerID, NULL);//唤醒消费者for (int i = 0; i < live_num; ++i){pthread_cond_signal(&notempty);}if (taskqueue){delete taskqueue;}if (threadID){delete[] threadID;}pthread_mutex_destroy(&mutex_pool);pthread_cond_destroy(&notempty);}//添加任务void Add_Task(Task<T> task){if (shutdown)return;//添加任务,不需加锁,队列中有taskqueue->AddTask(task);//唤醒消费者pthread_cond_signal(&notempty);}//获取忙线程个数int Get_Busy_Num(){int busynum = 0;pthread_mutex_lock(&mutex_pool);busynum = busy_num;pthread_mutex_unlock(&mutex_pool);return busynum;}//获取存活线程个数int Get_Live_Num(){int livenum = 0;pthread_mutex_lock(&mutex_pool);	 livenum = live_num;			 pthread_mutex_unlock(&mutex_pool);	 return livenum;						 }private://工作的线程任务函数static void* Work(void* args){ThreadPool* pool = static_cast<ThreadPool*>(args);while (true){//访问任务队列加锁pthread_mutex_lock(&pool->mutex_pool);//判断任务队列是否为空,空了就堵塞while (pool->taskqueue->GetTaskNum() == 0 && !pool->shutdown){cout << "thread :" << to_string(pthread_self()) << " waiting..." << endl;pthread_cond_wait(&pool->notempty, &pool->mutex_pool);//解除后 判断是否要销毁进程if (pool->exit_num > 0){pool->exit_num--;if (pool->live_num > pool->min_num){pool->live_num--;pthread_mutex_unlock(&pool->mutex_pool);pool->Thread_Exit();}}}//判断线程池是否要关闭了if (pool->shutdown){pthread_mutex_unlock(&pool->mutex_pool);pool->Thread_Exit();}//从任务队列取出任务Task<T> task = pool->taskqueue->TakeTask();pool->busy_num++;pthread_mutex_unlock(&pool->mutex_pool);cout << "thread :" << to_string(pthread_self()) << " start working..." << endl;task.function(task.args);delete task.args;task.args = nullptr;//任务结束cout << "thread :" << to_string(pthread_self()) << " end working..." << endl;pthread_mutex_lock(&pool->mutex_pool);pool->busy_num--;pthread_mutex_unlock(&pool->mutex_pool);}return nullptr;}//管理者线程任务函数static void* Manage(void* args){ThreadPool* pool = static_cast<ThreadPool*>(args);while (!pool->shutdown){//5秒检测一次sleep(5);pthread_mutex_lock(&pool->mutex_pool);int livenum = pool->live_num;int busynum = pool->busy_num;int queuesize = pool->taskqueue->GetTaskNum();pthread_mutex_unlock(&pool->mutex_pool);const int NUMBER = 2;//创建if (queuesize > livenum && livenum < pool->max_num){pthread_mutex_lock(&pool->mutex_pool);int num = 0;for (int i = 0; i < pool->max_num && num < NUMBER && pool->live_num < pool->max_num ; ++i){if (pool->threadID[i] == 0){pthread_create(&pool->threadID[i], NULL, Work, pool);num++;pool->live_num++;}}pthread_mutex_unlock(&pool->mutex_pool);}//销毁if (busynum * 2 < livenum && livenum > pool->min_num){pthread_mutex_lock(&pool->mutex_pool);pool->exit_num = NUMBER;pthread_mutex_unlock(&pool->mutex_pool);for (int i = 0; i < NUMBER; ++i){pthread_cond_signal(&pool->notempty);}}}return nullptr;}void Thread_Exit(){pthread_t tid = pthread_self();for (int i = 0; i < max_num; ++i){if (threadID[i] == tid){cout << "thread :" << to_string(pthread_self()) << "exiting" << endl;threadID[i] = 0;break;}}pthread_exit(NULL);}
private:pthread_mutex_t mutex_pool;pthread_cond_t notempty;pthread_t* threadID;pthread_t managerID;TaskQueue<T>* taskqueue;int min_num;int max_num;int busy_num;int live_num;int exit_num;bool shutdown = false;};

2. 测试部分

#include"ThreadPool.h"void Task_Test(void* args)
{int num = *(int*)args;cout<<"thread :" << pthread_self() << " is working " << "number =" << num <<endl;sleep(1);return;
}int main()
{//创建线程池ThreadPool<int> pool(3, 10);for (int i = 0; i < 100; ++i){int* num = new int(i+100);pool.Add_Task(Task<int>(Task_Test,num));}sleep(40);return 0;
}

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以上只是基于C修改出对应于C++的代码

并且以上代码存在一个问题
输出的结果有时会因为线程原因出现混乱
可以通过加锁来解决,但锁的数量超过1就容易导致死锁问题,所以暂且搁置

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二、C++11实现线程池

并非原创,摘于此处

1. 头文件

#pragma once
#include<queue>
#include<thread>
#include<condition_variable>
#include<atomic>
#include<stdexcept>
#include<future>
#include<vector>
#include<functional>namespace std
{#define THREADPOOL_MAX_NUM 16class threadpool{unsigned short _initsize;using Task = function<void()>;vector<thread> _pool;queue<Task> _tasks;mutex _lock;mutex _lockGrow;condition_variable _task_cv;atomic<bool> _run{true};atomic<int> _spa_trd_num{0};public:inline threadpool(unsigned short size = 4){_initsize = size;Add_Thread(size);}inline ~threadpool(){_run = false;_task_cv.notify_all();for (thread& thread : _pool){if (thread.joinable())thread.join();}}template<typename F,typename... Args>auto commit(F&& f, Args&& ...args) -> future<decltype(f(args...)) >{if (!_run)throw runtime_error{"commit auto stop"};using RetType = decltype(f(args...));auto task = make_shared<packaged_task<RetType()>>(bind(forward<F>(f), forward<Args>(args)...));future<RetType> future = task->get_future();{lock_guard<mutex> lock{_lock};_tasks.emplace([task]() {(*task)(); });}if (_spa_trd_num < 1 && _pool.size() < THREADPOOL_MAX_NUM)Add_Thread(1);_task_cv.notify_one();return future;}template<typename F>void commit2(F&& f){if (!_run)return;{lock_guard<mutex> lock{_lock};_tasks.emplace(forward<F>(f));}if (_spa_trd_num < 1 && _pool.size() < THREADPOOL_MAX_NUM)Add_Thread(1);_task_cv.notify_one();}int idlCount() { return _spa_trd_num; }int thrCount() { return _pool.size(); }private:void Add_Thread(unsigned short size){if (!_run)throw runtime_error{"Add_Thread stop"};unique_lock<mutex> lockgrow{_lockGrow};for (; _pool.size() < THREADPOOL_MAX_NUM && size > 0; --size){_pool.emplace_back([this]{while (true){Task task;{unique_lock<mutex> lock{_lock};_task_cv.wait(lock, [this] {return !_run || !_tasks.empty(); });if (!_run && _tasks.empty())return;_spa_trd_num--;task = move(_tasks.front());_tasks.pop();}task();if (_spa_trd_num > 0 && _pool.size() > _initsize)return;{unique_lock<mutex> lock{_lock};_spa_trd_num++;}}});{unique_lock<mutex> lock{_lock};_spa_trd_num++;}}	}};
}

要使用pthread依赖库

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2. 测试部分

#include"ThreadPool.hpp"
#include<iostream>void fun1(int slp)
{printf("fun1  %ld\n", std::this_thread::get_id());if (slp > 0){printf("fun1 sleep %ld  =========  %ld\n", slp, std::this_thread::get_id());std::this_thread::sleep_for(std::chrono::milliseconds(slp));}
}struct gfun
{int operator()(int n){printf("gfun  %ld\n", n, std::this_thread::get_id());return 42;}
};class A
{
public:static int Afun(int n = 0) //函数必须是 static 的才能直接使用线程池{std::cout << n << "Afun  " << std::this_thread::get_id() << std::endl;return n;}static std::string Bfun(int n, std::string str, char c) {std::cout << n << "Bfun   " << str.c_str() << "  " << (int)c << "  " << std::this_thread::get_id() << std::endl;return str;}
};int main()
try {std::threadpool executor{ 50 };std::future<void> ff = executor.commit(fun1, 0);std::future<int> fg = executor.commit(gfun{}, 0);//std::future<int> gg = executor.commit(A::Afun, 9999); //IDE提示错误,但可以编译运行std::future<std::string> gh = executor.commit(A::Bfun, 9998, "mult args", 123);std::future<std::string> fh = executor.commit([]()->std::string { std::cout << "hello, fh !  " << std::this_thread::get_id() << std::endl; return "hello,fh ret !\n"; });std::this_thread::sleep_for(std::chrono::seconds(1));std::cout << fg.get() << "  " << fh.get().c_str() << "  " << std::this_thread::get_id() << std::endl;std::cout << " =======  fun1,55 ========= " << std::this_thread::get_id() << std::endl;executor.commit(fun1, 55).get();    //调用.get()获取返回值会等待线程执行完std::threadpool pool(4);std::vector< std::future<int> > results;for (int i = 0; i < 8; ++i){results.emplace_back(pool.commit([i] {std::cout << "hello " << i << std::endl;std::this_thread::sleep_for(std::chrono::seconds(3));std::cout << "world " << i << std::endl;return i * i;}));}std::this_thread::sleep_for(std::chrono::seconds(15));for (auto&& result : results)std::cout << result.get() << ' ';std::cout << std::endl;return 0;
}
catch (std::exception& e)
{std::cout << "some error " << std::this_thread::get_id() << e.what() << std::endl;
}

• 测试结果