linux下c++线程池的简单实现
小编给大家分享一下linux 下c++线程池的简单实现,相信大部分人都还不怎么了解,因此分享这篇文章给大家参考一下,希望大家阅读完这篇文章后大有收获,下面让我们一起去了解一下吧!
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作为一个c++菜鸟,研究半天这个代码的实现原理,发现好多语法不太熟悉,因此加了一大堆注释,仅供参考。该段代码主要通过继承workthread类来实现自己的线程代码,通过thread_pool类来管理线程池,线程池不能够实现动态改变线程数目,存在一定局限性。目前可能还有缺陷,毕竟c++来封装这个东西,资源释放什么的必须想清楚,比如vector存储了基类指针实现多态,那么如何释放对象仍需要考虑,后续我可能会更进一步修改完善该代码,下面贡献一下自己的劳动成果。
#include#include #include #include using namespace std; /* WorkerThread class This class needs to be sobclassed by the user. */ class WorkerThread{ public: int id; unsigned virtual executeThis() { return 0; } WorkerThread(int id) : id(id) {} virtual ~WorkerThread(){} }; /* ThreadPool class manages all the ThreadPool related activities. This includes keeping track of idle threads and synchronizations between all threads. */ class ThreadPool{ public: ThreadPool(); ThreadPool(int maxThreadsTemp); virtual ~ThreadPool(); void destroyPool(int maxPollSecs); bool assignWork(WorkerThread *worker); bool fetchWork(WorkerThread **worker); void initializeThreads(); static void *threadExecute(void *param); // pthread_create()调用的函数必须为静态的 static pthread_mutex_t mutexSync; static pthread_mutex_t mutexWorkCompletion;//工作完成个数互斥量 private: int maxThreads; pthread_cond_t condCrit; sem_t availableWork; sem_t availableThreads; vector workerQueue; int topIndex; int bottomIndex; int incompleteWork; int queueSize; };
#include#include "threadpool.h" using namespace std; //初始化类的静态成员必须加上类型和作用域,static数据成员必须在类定义体的外部定义,不像不同数据成员可以用构造函数初始化 //应该在定义时进行初始化,注意是定义,这个定义应该放在包含类的非内联成员函数定义的文件中。 //注:静态成员函数只能使用静态变量,非静态没有限制,静态变量必须在外部定义和初始化,没初始化就为默认数值 pthread_mutex_t ThreadPool::mutexSync = PTHREAD_MUTEX_INITIALIZER; pthread_mutex_t ThreadPool::mutexWorkCompletion = PTHREAD_MUTEX_INITIALIZER; ThreadPool::ThreadPool() { ThreadPool(2); } ThreadPool::ThreadPool(int maxThreads) { if (maxThreads < 1) maxThreads=1; pthread_mutex_lock(&mutexSync); this->maxThreads = maxThreads; this->queueSize = maxThreads; workerQueue.resize(maxThreads, NULL);//调整容器大小,然后用默认构造函数初始化新的空间 topIndex = 0; bottomIndex = 0; incompleteWork = 0; sem_init(&availableWork, 0, 0); //工作队列信号量,表示已经加入队列的工作,初始时没有工作 sem_init(&availableThreads, 0, queueSize); //空闲线程信号量,一开始就有quisize个线程可以使用 pthread_mutex_unlock(&mutexSync); } //调用pthread_create()让线程跑起来,threadExecute是类的静态函数,因为pthread_create()第三个参数必须为静态函数 void ThreadPool::initializeThreads() { for(int i = 0; i 0 ) { //cout << "Work is still incomplete=" << incompleteWork << endl; sleep(maxPollSecs); } cout << "All Done!! Wow! That was a lot of work!" << endl; sem_destroy(&availableWork); sem_destroy(&availableThreads); pthread_mutex_destroy(&mutexSync); pthread_mutex_destroy(&mutexWorkCompletion); } //分配人物到top,然后通知有任务需要执行。 bool ThreadPool::assignWork(WorkerThread *workerThread) { pthread_mutex_lock(&mutexWorkCompletion); incompleteWork++; //cout << "assignWork...incomapleteWork=" << incompleteWork << endl; pthread_mutex_unlock(&mutexWorkCompletion); sem_wait(&availableThreads); pthread_mutex_lock(&mutexSync); //workerVec[topIndex] = workerThread; workerQueue[topIndex] = workerThread; //cout << "Assigning Worker[" << workerThread->id << "] Address:[" << workerThread << "] to Queue index [" << topIndex << "]" << endl; if(queueSize !=1 ) topIndex = (topIndex+1) % (queueSize-1); sem_post(&availableWork); pthread_mutex_unlock(&mutexSync); return true; } //当已经有人物放到队列里面后,就会受到通知,然后从底部拿走工作,在workerArg中返回 bool ThreadPool::fetchWork(WorkerThread **workerArg) { sem_wait(&availableWork); pthread_mutex_lock(&mutexSync); WorkerThread * workerThread = workerQueue[bottomIndex]; workerQueue[bottomIndex] = NULL; *workerArg = workerThread; if(queueSize !=1 ) bottomIndex = (bottomIndex+1) % (queueSize-1); sem_post(&availableThreads); pthread_mutex_unlock(&mutexSync); return true; } //每个线程运行的静态函数实体,executeThis 方法将会被继承累从写,之后实现具体线程的工作。 void *ThreadPool::threadExecute(void *param) { WorkerThread *worker = NULL; while(((ThreadPool *)param)->fetchWork(&worker)) { if(worker) { worker->executeThis(); //cout << "worker[" << worker->id << "]\tdelete address: [" << worker << "]" << endl; delete worker; worker = NULL; } pthread_mutex_lock( &(((ThreadPool *)param)->mutexWorkCompletion) ); //cout << "Thread " << pthread_self() << " has completed a Job !" << endl; ((ThreadPool *)param)->incompleteWork--; pthread_mutex_unlock( &(((ThreadPool *)param)->mutexWorkCompletion) ); } return 0; }
#include#include "threadpool.h" using namespace std; #define ITERATIONS 20 class SampleWorkerThread : public WorkerThread { public: int id; unsigned virtual executeThis() { // Instead of sleep() we could do anytime consuming work here. // Using ThreadPools is advantageous only when the work to be done is really time consuming. (atleast 1 or 2 seconds) cout<<"This is SampleWorkerThread sleep 2s"< initializeThreads(); //用来计算时间间隔。 time_t t1=time(NULL); //分配具体工作到线程池 for(unsigned int i=0;i assignWork(myThreathreadExecuted); } //销毁钱等待所有线程结束,等待间隔为2秒。 myPool->destroyPool(2); time_t t2=time(NULL); cout << t2-t1 << " seconds elapsed\n" << endl; delete myPool; return 0; }
ubuntu 12.04下运行成功,编译命令如下:g++ -g main.cpp thread_pool.cpp -o thread_pool -lpthread
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