linux C语言 手写线程池

main.cpp

#include <stdio.h>
#include "threadpool.h"
#include <malloc.h>
#include <pthread.h>
#include <unistd.h>

void taskFunc(void* arg)
{
    int num = *((int*)arg);
    printf("thread %ld is working, number = %d\n", pthread_self(), num);
    sleep(1);
}

int main()
{
    printf("%s 向你问好!\n", "threadpool");
    // 创建线程池
    ThreadPool* pool = threadPoolCreate(3, 10, 100);
    for (int i = 0; i < 100; i++)
    {
        int* num = (int*)malloc(sizeof(int));
        *num = i + 100;
        threadPoolAdd(pool, taskFunc, num);
    }
    sleep(30);
    threadPoolDestory(pool);
    return 0;
}

threadpool.h

#pragma once
#include <cstddef>
class threadpool
{
};
typedef struct ThreadPool ThreadPool;
// 创建线程池并初始化
ThreadPool* threadPoolCreate(int min, int max, int queueSize);

// 销毁线程池
int threadPoolDestory(ThreadPool* pool);

// 给线程池添加任务
void threadPoolAdd(ThreadPool* pool, void(*func)(void*), void* arg);

// 获取线程池中工作的线程个数
int threadPoolBusyNum(ThreadPool* pool);

// 获取线程池中活着的线程的个数
int threadPoolAliveNum(ThreadPool* pool);

void* worker(void* arg);
void* manager(void* arg);
void threadExit(ThreadPool* pool);

 threadpool.cpp

#include "threadpool.h"
#include <pthread.h>
#include <malloc.h>
#include <string.h>
#include <unistd.h> 

const int NUMBER = 2;

// 任务结构体
typedef struct Task
{
	void (*function)(void* arg);
	void* arg;
}Task;

// 线程池结构体
struct ThreadPool
{
	// 任务队列
	Task* taskQ;
	int queueCapacity; // 队列容量
	int queueSize;     // 当前任务个数
	int queueFront;    // 队头 -- 取数据
	int queueRear;	   // 队尾 -- 放数据

	pthread_t managerId;  // 管理者线程ID
	pthread_t* threadIDs; // 工作的线程ID
	int minNum; // 最小线程数
	int maxNum; // 最大线程数
	int busyNum;// 忙碌线程数
	int liveNum;// 存活线程数
	int exitNum;// 要销毁线程个数
	pthread_mutex_t mutexPool; // 锁整个线程池
	pthread_mutex_t mutexBusy; // 锁busyNum变量
	pthread_cond_t notFull;    // 任务队列是不是满了
	pthread_cond_t notEmpty;   // 任务队列是不是空了

	int shutdown; // 是不是要销毁线程, 销毁为1, 不销毁为0
};

ThreadPool* threadPoolCreate(int min, int max, int queueSize)
{
	ThreadPool* pool = (ThreadPool*)malloc(sizeof(ThreadPool));
	do
	{
		if (pool == NULL)
		{
			printf("malloc threadpool fail .. \n");
			break;
		}
		pool->threadIDs = (pthread_t*)malloc(sizeof(pthread_t) * max);
		if (pool->threadIDs == NULL)
		{
			printf("malloc threadIDs fail .. \n");
			break;
		}
		memset(pool->threadIDs, 0, sizeof(pthread_t) * max);
		pool->minNum = min;
		pool->maxNum = max;
		pool->busyNum = 0;
		pool->liveNum = min; // 和最小个数相等
		pool->exitNum = 0;

		if (pthread_mutex_init(&pool->mutexPool, NULL) != 0 ||
			pthread_mutex_init(&pool->mutexBusy, NULL) != 0 ||
			pthread_cond_init(&pool->notEmpty, NULL) != 0 ||
			pthread_cond_init(&pool->notFull, NULL) != 0)
		{
			printf("mutex init fail ... \n");
			break;
		}
		pool->taskQ = (Task*)malloc(sizeof(Task) * queueSize);
		pool->queueCapacity = queueSize;
		pool->queueSize = 0;
		pool->queueFront = 0;
		pool->queueRear = 0;
		pool->shutdown = 0;

		// 创建线程
		pthread_create(&pool->managerId, NULL, manager, pool);
		for (int i = 0; i < min; i++)
		{
			pthread_create(&pool->threadIDs[i], NULL, worker, pool);
		}
		return pool;
	} while (0);

	// 释放资源
	if (pool && pool->threadIDs)
	{
		free(pool->threadIDs);
	}
	if (pool && pool->taskQ)
	{
		free(pool->taskQ);
	}
	if (pool)
	{
		free(pool);
	}

	return NULL;
}

int threadPoolDestory(ThreadPool* pool)
{
	if (pool == NULL)
	{
		return -1;
	}
	// 关掉线程池
	pool->shutdown = 1;
	// 阻塞回收管理者线程
	// 唤醒阻塞的消费者线程
	for (int i = 0; i < pool->liveNum; i++)
	{
		pthread_cond_signal(&pool->notEmpty);
	}
	pthread_join(pool->managerId, NULL);

	// 释放堆内存
	if (pool->taskQ)
	{
		free(pool->taskQ);
	}
	if (pool->threadIDs)
	{
		free(pool->threadIDs);
	}

	pthread_mutex_destroy(&pool->mutexPool);
	pthread_mutex_destroy(&pool->mutexBusy);
	pthread_cond_destroy(&pool->notEmpty);
	pthread_cond_destroy(&pool->notFull);
	free(pool);
	pool = NULL;
	return 0;
}

void threadPoolAdd(ThreadPool* pool, void(*func)(void*), void* arg)
{
	pthread_mutex_lock(&pool->mutexPool);
	while (pool->queueSize==pool->queueCapacity && !pool->shutdown)
	{
		// 阻塞生产者线程
		pthread_cond_wait(&pool->notFull, &pool->mutexPool);
	}
	if (pool->shutdown)
	{
		pthread_mutex_unlock(&pool->mutexPool);
		return;
	}
	// 添加任务
	pool->taskQ[pool->queueRear].function = func;
	pool->taskQ[pool->queueRear].arg = arg;
	pool->queueRear = (pool->queueRear + 1) % pool->queueCapacity;
	pool->queueSize++;
	pthread_cond_signal(&pool->notEmpty);
	pthread_mutex_unlock(&pool->mutexPool);
}

int threadPoolBusyNum(ThreadPool* pool)
{
	pthread_mutex_lock(&pool->mutexBusy);
	int busyNum = pool->busyNum;
	pthread_mutex_unlock(&pool->mutexBusy);

	return busyNum;
}

int threadPoolAliveNum(ThreadPool* pool)
{
	pthread_mutex_lock(&pool->mutexPool);
	int aliveNum = pool->liveNum;
	pthread_mutex_unlock(&pool->mutexPool);
	return aliveNum;
}

void* worker(void* arg)
{
	ThreadPool* pool = (ThreadPool*)arg;
	while (1)
	{
		pthread_mutex_lock(&pool->mutexPool);
		// 当前任务队列是否为空
		while (pool->queueSize == 0 && !pool->shutdown)
		{
			// 阻塞工作线程
			pthread_cond_wait(&pool->notEmpty, &pool->mutexPool);

			// 判断是不是要销毁线程
			if (pool->exitNum > 0)
			{
				pool->exitNum--;
				if (pool->liveNum > pool->minNum)
				{
					pool->liveNum--;
					pthread_mutex_unlock(&pool->mutexPool);
					threadExit(pool);
				}
			}
		}

		// 判断线程池是否被关闭了
		if (pool->shutdown)
		{
			pthread_mutex_unlock(&pool->mutexPool);
			threadExit(pool);
		}

		// 从任务队列中取出一个任务
		Task task;
		task.function = pool->taskQ[pool->queueFront].function;
		task.arg = pool->taskQ[pool->queueFront].arg;
		// 移动头节点
		pool->queueFront = (pool->queueFront + 1) % pool->queueCapacity;
		pool->queueSize--;
		// 解锁
		pthread_cond_signal(&pool->notFull);
		pthread_mutex_unlock(&pool->mutexPool);

		printf("thread %ld start working ... \n", pthread_self());
		pthread_mutex_lock(&pool->mutexBusy);
		pool->busyNum++;
		pthread_mutex_unlock(&pool->mutexBusy);
		task.function(task.arg);

		free(task.arg);
		task.arg = NULL;

		// 结束工作
		printf("thread %ld end working ... \n", pthread_self());
		pthread_mutex_lock(&pool->mutexBusy);
		pool->busyNum--;
		pthread_mutex_unlock(&pool->mutexBusy);

	}

	return NULL;
}

void* manager(void* arg)
{
	ThreadPool* pool = (ThreadPool*)arg;
	while (!pool->shutdown)
	{
		// 每隔3s检测一次
		sleep(3);

		// 取出线程池中任务的数量和当前线程的数量
		pthread_mutex_lock(&pool->mutexPool);
		int queueSize = pool->queueSize;
		int liveNum = pool->liveNum;
		pthread_mutex_unlock(&pool->mutexPool);

		// 取出忙的线程的数量
		pthread_mutex_lock(&pool->mutexBusy);
		int busyNum = pool->busyNum;
		pthread_mutex_unlock(&pool->mutexBusy);

		// 添加线程
		// 当前任务的个数>穿暖和的线程个数 && 存活的线程数<最大线程数
		if (queueSize > liveNum && liveNum < pool->maxNum)
		{
			pthread_mutex_lock(&pool->mutexPool);
			int counter = 0;
			for (int i = 0; i < pool->maxNum && counter<NUMBER && pool->liveNum<pool->maxNum; i++)
			{
				if (pool->threadIDs[i] == 0) {
					pthread_create(&pool->threadIDs[i], NULL, worker, pool);
					counter++;
					pool->liveNum++;
				}
			}
			pthread_mutex_unlock(&pool->mutexPool);

		}
		// 销毁线程
		// 忙的线程*2 < 存活的线程数  &&  存活的线程 > 最小线程数
		if (busyNum*2 < liveNum && liveNum > pool->minNum)
		{
			pthread_mutex_lock(&pool->mutexPool);
			pool->exitNum = NUMBER;
			pthread_mutex_unlock(&pool->mutexPool);
			// 让工作的线程自杀
			for (int i = 0; i < NUMBER; i++)
			{
				pthread_cond_signal(&pool->notEmpty);
			}
		}
	}
	return nullptr;
}

void threadExit(ThreadPool* pool)
{
	pthread_t tid = pthread_self();
	for (int i = 0; i < pool->maxNum; i++)
	{
		if (pool->threadIDs[i] == tid) 
		{
			pool->threadIDs[i] = 0;
			printf("threadExit called, %ld exiting ...\n", tid);
			break;
		}
	}
	pthread_exit(NULL);
}