Linux下简单实现的线程池

thread_pool.h

/*************************************************************************
> File Name: thrread_pool.h
> Author:    arrayli
> Mail:      1374367549@qq.com
> Created Time: 2018年03月04日 星期日 15时11分38秒
************************************************************************/

#ifndef _THRREAD_POOL_H
#define _THRREAD_POOL_H

#include<stdio.h>
#include<unistd.h>
#include<pthread.h>
#include<stdlib.h>
#include<errno.h>
#include<string.h>

#define DEFAULT_TIME 10                      /* 10s 检测一次 */
#define MIN_WAIT_TASK_NUM 10                 /* 如果 queue_size > MIN_WAIT_TASK_NUM 添加新的线程到线程池 */
#define DEFAULT_THREAD_VARY 10               /* 每次创建和销毁的线程个数 */

#define true  1
#define false 0

typedef struct
{
void*(*function)(void*);                 /* 函数指针，执行回调函数 */
void *arg;                               /* 上面函数的 参数 */
}threadpool_task_t;                         /* 各子线程任务结构体 */

/* 描述线程池相关信息 */

typedef struct threadpool_t
{
pthread_mutex_t lock;                     /* 用于锁住本结构体 */
pthread_mutex_t thread_counter;            /* 记录忙状态线程个数的锁 ---- busy_thr_num */
pthread_cond_t queue_not_full;            /* 当任务队列满时，添加任务的线程阻塞，等待此条件变量 */
pthread_cond_t queue_not_empty;           /* 任务队列里不为空，通知等待任务的线程 */

pthread_t *threads;                        /* 存放线程池中每个线程的 tid ，数组 */
pthread_t adjust_tid;                     /* 存放管理线程 tid */
threadpool_task_t *task_queue;            /* 任务队列 */

int max_thr_num;                          /* 线程池最大线程数 */
int min_thr_num;                          /* 线程池最小线程数 */
int busy_thr_num;                         /* 忙状态线程个数 */
int live_thr_num;                         /* 当前存活线程个数 */
int wait_exit_thr_num;                    /* 要销毁的线程个数 */

int queue_front;                          /* task_queue 队头下标 */
int queue_rear;                           /* task_queue 队尾下标 */
int queue_size;                           /* task_queue 队中实际任务数 */
int queue_max_size;                       /* task_queue 队列可容纳任务数上限 */

int shutdown;                             /* 标志位 线程池使用状态 true 或 false */
}threadpool_t ;

/* typedef struct threadpool_t threadpool_t; */

void *threadpool_create(int min_thr_num,int max_thr_num,int queue_max_size);

void *threadpool_thread(void *arg);

void *adjust_thread(void*arg);

int threadpool_add(threadpool_t* pool,void*(*function)(void *arg),void *arg);

int threadpool_free(threadpool_t *pool);

int is_thread_alive(pthread_t tid);

int threadpool_destroy(threadpool_t *pool);

#endif

thread_pool.c

/*************************************************************************
> File Name: thrread_pool.c
> Author: arrayli
> Mail: 1374367549@qq.com
> Created Time: 2018年03月04日 星期日 15时12分33秒
************************************************************************/

#include<stdio.h>
#include<unistd.h>
#include<signal.h>
#include"thread_pool.h"

/* typedef struct threadpool_t threadpool_t; */

void *threadpool_create(int min_thr_num,int max_thr_num,int queue_max_size)
{
int i;
threadpool_t *pool = NULL;

do
{
/* 给线程池数据结构分配内存 空间,若分配内存失败，则跳出 do-while 循环 */
if( (pool = (threadpool_t*)malloc(sizeof(threadpool_t))) == NULL)
{
printf("malloc threadpool failed!\n");
break;
}

/* 给线程池数据结构初始化 */
pool->min_thr_num = min_thr_num;
pool->max_thr_num = max_thr_num;
pool->busy_thr_num = 0;
pool->live_thr_num = min_thr_num; /* 活着的线程数 初值 = min_thr_num */
pool->queue_size = 0; /* 有 0 个产品 */
pool->queue_max_size = queue_max_size;
pool->queue_front = 0;
pool->queue_rear = 0;
pool->shutdown = false; /* 不关闭线程池 */

/* 根据最大线程上限数,给工作线程数组开辟空间，并清零 */
pool->threads = (pthread_t*)malloc(sizeof(pthread_t)*max_thr_num);
if(!pool->threads)
{
printf("malloc threads failed\n");
break;
}

/* 线程数组，清零 */
memset(pool->threads,0x00,sizeof(pool->threads)*max_thr_num);

/* 队列开辟空间 */

pool->task_queue = (threadpool_task_t*)malloc(sizeof(threadpool_task_t)*queue_max_size);
/* 如果队列开辟空间失败 */
if(!pool->task_queue)
{
printf("malloc task_queue failed!\n");
break;
}

/* 初始化互斥锁，条件变量 */
if(pthread_mutex_init(&pool->lock,NULL) != 0 ||
pthread_mutex_init(&pool->thread_counter,NULL) != 0 ||
pthread_cond_init(&pool->queue_not_empty,NULL) != 0 ||
pthread_cond_init(&pool->queue_not_full,NULL) != 0
)
{
printf("init lock or cond failed!\n");
break;
}

/* 启动 min_thr_num 个 工作线程 */
for( i = 0; i < min_thr_num; i++ )
{
pthread_create(&pool->threads[i],NULL,threadpool_thread,(void*)pool); /* pool 指向当前线程池 */
printf("start thread 0x%x...\n",(unsigned int)pool->threads[i]);
}

/* 启动管理者线程 */
pthread_create(&pool->adjust_tid,NULL,adjust_thread,(void*)pool);
return pool;

}while(0);

/* 前面调用代码失败 */
threadpool_free(pool);
return NULL;
}

/* 线程池中各个工作线程 */

void *threadpool_thread(void *threadpool)
{
threadpool_t *pool = (threadpool_t*)threadpool;
threadpool_task_t task;

while(true)
{
/* 刚创建出线程，等待队列里有任务，否则阻塞在等待队列有任务后再唤醒接收任务 */
pthread_mutex_lock(&pool->lock);

/* queue_size == 0 ，说明没有任务，调用 wait 阻塞在条件变量上，若有任务，则跳过 while */
while(pool->queue_size == 0 && ! pool->shutdown)
{
printf("thread 0x%x is waiting!\n",(unsigned int)pthread_self());
pthread_cond_wait(&pool->queue_not_empty,&pool->lock);

/* 清除指定数目的空闲线程，如果要结束的线程大于 0 ，结束线程 */
if(pool->wait_exit_thr_num > 0 )
{
pool->wait_exit_thr_num--;

/* 如果线程池里的线程数大于最小值时，可以结束当前线程 */
if(pool->live_thr_num > pool->min_thr_num)
{
printf("thread 0x%x exiting\n",(unsigned int)pthread_self());
pool->live_thr_num--;
pthread_mutex_unlock(&pool->lock);
pthread_exit(NULL);
}

}
}

/* 如果指定了 true ，要关闭线程池里面的每一个线程，自行退出处理 */
if(pool->shutdown)
{
pthread_mutex_unlock(&pool->lock);
pthread_mutex_unlock(&pool->lock);
pthread_exit(NULL); /* 线程自行结束 */
}

/* 从任务队列里取出任务，是一个出对操作 */
task.function = pool->task_queue[pool->queue_front].function;
task.arg = pool->task_queue[pool->queue_front].arg;

pool->queue_front = (pool->queue_front+1) % pool->queue_max_size; /* 出对，模拟环形队列 */
pool->queue_size--;

/* 通知可以有新的任务添加进来 */
pthread_cond_broadcast(&pool->queue_not_full);

/* 任务取出后，立即将线程池锁释放 */
pthread_mutex_unlock(&pool->lock);

/* 执行任务 */
printf("thread 0x%x start working\n",(unsigned int)pthread_self());

pthread_mutex_lock(&(pool->thread_counter)); /* 忙状态线程变量锁 */
pool->busy_thr_num ++;
pthread_mute
4000
x_unlock(&(pool->thread_counter));

(*(task.function))(task.arg); /* 执行回调函数任务 */

/* 任务结束处理 */

printf("thread 0x%x end working\n",(unsigned int)pthread_self());

pthread_mutex_lock(&(pool->thread_counter)); /* 忙状态线程变量锁 */
pool->busy_thr_num --;
pthread_mutex_unlock(&(pool->thread_counter));
}
pthread_exit(NULL);
}

/* 管理线程 */
void *adjust_thread(void*threadpool)
{
int i;
threadpool_t *pool = (threadpool_t*) threadpool;

while(!pool->shutdown)
{
sleep(DEFAULT_TIME); /* 定时 线程池进行管理 */

pthread_mutex_lock(&pool->lock);
int queue_size = pool->queue_size; /* 关注 任务数 */
int live_thr_num = pool->live_thr_num; /* 存活 线程数 */
pthread_mutex_unlock(&pool->lock);

pthread_mutex_lock(&(pool->thread_counter));
int busy_thr_num = pool->busy_thr_num; /* 忙着线程数 */
pthread_mutex_unlock(&(pool->thread_counter));

/* 当任务数量增加时，创建新的线程算法：任务数量大于最小线程数量，且存活的线程数少于最大线程数时，如：30>=10 && 40< 100 */
if(pool->queue_size>pool->min_thr_num && pool->live_thr_num < pool->max_thr_num)
{
pthread_mutex_lock(&pool->lock);
int add = 0;
/* 一次增加 DEFAULT_THREAD_VARY 个线程 */
for(i=0; i<pool->max_thr_num && add<DEFAULT_THREAD_VARY && pool->live_thr_num < pool->max_thr_num; i++)
{
if(pool->threads[0] == 0 || !is_thread_alive(pool->threads[i]))
{
pthread_create(&pool->threads[i],NULL,threadpool_thread,(void*)pool); /* pool 指向当前线程池 */
add++;
pool->live_thr_num++;
}
}
pthread_mutex_unlock(&pool->lock);

}

/* 销毁多余的空闲线程算法： 忙线程 * 2 小于存活的线程数 且 存活的线程数大于最小线程数时 */
if((busy_thr_num*2 > live_thr_num) && (live_thr_num < pool->min_thr_num))
{
/* 一次销毁 DEFAULT_THREAD_VARY 个线程，随机 10个即可 */

pthread_mutex_lock(&pool->lock);
pool->wait_exit_thr_num = DEFAULT_THREAD_VARY; /* 要销毁的线程数设置为 10 */
pthread_mutex_unlock(&pool->lock);

for( i=0; i<DEFAULT_THREAD_VARY;i++ )
{
/* 通知空闲处的线程，它们自行终止 */
pthread_cond_broadcast(&(pool->queue_not_empty));
}
}
}
return NULL;
}

/* 向线程池中添加一个任务 */

int threadpool_add(threadpool_t* pool,void*(*function)(void *arg),void *arg)
{
pthread_mutex_lock(&pool->lock);

/* == 为真 ，队列已经满，调用 wait 阻塞 */
while((pool->queue_size == pool->queue_max_size) && !(pool->shutdown))
{
pthread_cond_wait(&(pool->queue_not_full),&pool->lock);
}

if(pool->shutdown)
{
pthread_mutex_unlock(&pool->lock);
}

/* 清空 工作线程 调用的回调函数 的参数arg */
if (pool->task_queue[pool->queue_rear].arg != NULL) {
free(pool->task_queue[pool->queue_rear].arg);
pool->task_queue[pool->queue_rear].arg = NULL;
}

/*添加任务到任务队列里*/
pool->task_queue[pool->queue_rear].function = function;
pool->task_queue[pool->queue_rear].arg = arg;
pool->queue_rear = (pool->queue_rear + 1) % pool->queue_max_size; /* 队尾指针移动,
模拟环形 */

pool->queue_size++;
/*添加完任务后，队列不为空，唤醒线程池中 等待处理任务的线程*/
pthread_cond_signal(&(pool->queue_not_empty));
pthread_mutex_unlock(&(pool->lock));
}

int threadpool_free(threadpool_t *pool)
{
if(pool == NULL)
{
return -1;
}
if(pool->task_queue)
{
free(pool->task_queue);
}
if(pool->threads)
{
free(pool->threads);
pthread_mutex_lock(&pool->lock);
pthread_mutex_destroy(&pool->lock);
pthread_mutex_lock(&pool->thread_counter);
pthread_mutex_destroy(&pool->thread_counter);
pthread_cond_destroy(&pool->queue_not_empty);
pthread_cond_destroy(&pool->queue_not_full);
}
free(pool);
pool = NULL;
return 0;
}

int is_thread_alive(pthread_t tid)
{
int kill_rc = pthread_kill(tid,0); /* 发送 0 信号，测试信号是否存活 */
if(kill_rc == ESRCH)
{
return false;
}
return true;
}

int threadpool_destroy(threadpool_t *pool)
{
int i;
if( pool == NULL )
{
return -1;
}
pool->shutdown = true;

/* 先销毁管理者线程 */
pthread_join(pool->adjust_tid,NULL);

for( i=0;i<pool->live_thr_num;i++ )
{
/* 通知所有空闲线程 */
pthread_cond_broadcast(&pool->queue_not_empty);
}

for(i=0;i<pool->live_thr_num;i++)
{
pthread_join(pool->threads[i],NULL);
}

threadpool_free(pool);
return 0;
}
// 测试程序

/*************************************************************************
> File Name: main.c
> Author: arrayli
> Mail: 1374367549@qq.com
> Created Time: 2018年03月04日 星期日 20时33分26秒
************************************************************************/

#include<stdio.h>
#include"thread_pool.h"

void *process(void *arg)
{
printf("thread 0x%x working on task %d\n ",(unsigned int)pthread_self(),*(int *)arg);
sleep(1);
printf("task %d is end\n",*(int *)arg);
return NULL;
}

int main(void)
{
/* 创建线程池，池里最小 3 个线程，最大 100个，队列最大 100 */
threadpool_t * thp = threadpool_create(3,100,100);

printf("pool inited\n");

int num[20],i;

for(i=0;i<20;i++)
{
num[i] = i;
printf("add task %d\n",i);
threadpool_add(thp,process,(void*)&num[i]); /* 向线程池中添加任务 */
}

sleep(10); /* 等待子线程完成任务 */
threadpool_destroy(thp);
return 0;
}