C语言实现支持动态拓展和销毁的线程池

本文实例介绍了C 语言实现线程池，支持动态拓展和销毁，分享给大家供大家参考，具体内容如下

实现功能

• 1.初始化指定个数的线程
• 2.使用链表来管理任务队列
• 3.支持拓展动态线程
• 4.如果闲置线程过多,动态销毁部分线程

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <signal.h>

/*线程的任务队列由,函数和参数组成,任务由链表来进行管理*/
typedef struct thread_worker_s{
  void *(*process)(void *arg); //处理函数
  void *arg;          //参数
  struct thread_worker_s *next;
}thread_worker_t;

#define bool int
#define true 1
#define false 0

/*线程池中各线程状态描述*/
#define THREAD_STATE_RUN        0
#define THREAD_STATE_TASK_WAITING   1
#define THREAD_STATE_TASK_PROCESSING  2
#define THREAD_STATE_TASK_FINISHED   3
#define THREAD_STATE_EXIT       4   

typedef struct thread_info_s{
  pthread_t id;
  int    state;
  struct thread_info_s *next;
}thread_info_t;

static char* thread_state_map[] ={"创建","等待任务","处理中","处理完成","已退出"};
/*线程压缩的时候只有 0,1,2,4 状态的线程可以销毁*/

/*线程池管理器*/
#define THREAD_BUSY_PERCENT 0.5  /*线程:任务 = 1:2 值越小，说明任务多,增加线程*/
#define THREAD_IDLE_PERCENT 2   /*线程:任务 = 2:1 值大于1,线程多于任务,销毁部分线程*/

typedef struct thread_pool_s{
  pthread_mutex_t queue_lock ; //队列互斥锁,即涉及到队列修改时需要加锁
  pthread_cond_t queue_ready; //队列条件锁,队列满足某个条件，触发等待这个条件的线程继续执行,比如说队列满了,队列空了

  thread_worker_t *head   ;    //任务队列头指针
  bool    is_destroy   ;    //线程池是否已经销毁
  int num;              //线程的个数
  int rnum;         ;    //正在跑的线程
  int knum;         ;    //已杀死的线程
  int queue_size       ;    //工作队列的大小
  thread_info_t *threads   ;    //线程组id,通过pthread_join(thread_ids[0],NULL) 来执行线程
  pthread_t   display   ;    //打印线程
  pthread_t   destroy   ;    //定期销毁线程的线程id
  pthread_t   extend    ;
  float percent       ;    //线程个数于任务的比例 rnum/queue_size
  int  init_num      ;
  pthread_cond_t  extend_ready     ;    //如果要增加线程
}thread_pool_t;

/*-------------------------函数声明----------------------*/
/**
 * 1.初始化互斥变量
 * 2.初始化等待变量
 * 3.创建指定个数的线程线程
 */
thread_pool_t* thread_pool_create(int num);
void *thread_excute_route(void *arg);

/*调试函数*/
void debug(char *message,int flag){
  if(flag)
    printf("%s\n",message);
}

void *display_thread(void *arg);
/**
 * 添加任务包括以下几个操作
 * 1.将任务添加到队列末尾
 * 2.通知等待进程来处理这个任务 pthread_cond_singal();
*/
int thread_pool_add_worker(thread_pool_t *pool,void*(*process)(void *arg),void *arg); //网线程池的队列中增加一个需要执行的函数，也就是任务

/**
 * 销毁线程池,包括以下几个部分
 * 1.通知所有等待的进程 pthread_cond_broadcase
 * 2.等待所有的线程执行完
 * 3.销毁任务列表
 * 4.释放锁，释放条件
 * 4.销毁线程池对象
 */

void *thread_pool_is_need_recovery(void *arg);
void *thread_pool_is_need_extend(void *arg);
void thread_pool_destory(thread_pool_t *pool);

thread_pool_t *thread_pool_create(int num){
  if(num<1){
    return NULL;
  }
  thread_pool_t *p;
  p = (thread_pool_t*)malloc(sizeof(struct thread_pool_s));
  if(p==NULL)
    return NULL;
  p->init_num = num;
  /*初始化互斥变量与条件变量*/
  pthread_mutex_init(&(p->queue_lock),NULL);
  pthread_cond_init(&(p->queue_ready),NULL);

  /*设置线程个数*/
  p->num  = num;
  p->rnum = num;
  p->knum = 0;

  p->head = NULL;
  p->queue_size =0;
  p->is_destroy = false;

  int i=0;
  thread_info_t *tmp=NULL;
  for(i=0;i<num;i++){
    /*创建线程*/
    tmp= (struct thread_info_s*)malloc(sizeof(struct thread_info_s));
    if(tmp==NULL){
      free(p);
      return NULL;
    }else{
      tmp->next = p->threads;
      p->threads = tmp;
    }
    pthread_create(&(tmp->id),NULL,thread_excute_route,p);
    tmp->state = THREAD_STATE_RUN;
  }

  /*显示*/
  pthread_create(&(p->display),NULL,display_thread,p);
  /*检测是否需要动态线程*/
  //pthread_create(&(p->extend),NULL,thread_pool_is_need_extend,p);
  /*动态销毁*/
  pthread_create(&(p->destroy),NULL,thread_pool_is_need_recovery,p);
  return p;
}

int thread_pool_add_worker(thread_pool_t *pool,void*(*process)(void*arg),void*arg){
  thread_pool_t *p= pool;
  thread_worker_t *worker=NULL,*member=NULL;
  worker = (thread_worker_t*)malloc(sizeof(struct thread_worker_s));
  int incr=0;
  if(worker==NULL){
    return -1;
  }
  worker->process = process;
  worker->arg   = arg;
  worker->next  = NULL;
  thread_pool_is_need_extend(pool);
  pthread_mutex_lock(&(p->queue_lock));
  member = p->head;
  if(member!=NULL){
    while(member->next!=NULL)
      member = member->next;
    member->next = worker;
  }else{
    p->head = worker;
  }
  p->queue_size ++;
  pthread_mutex_unlock(&(p->queue_lock));
  pthread_cond_signal(&(p->queue_ready));
  return 1;
}

void thread_pool_wait(thread_pool_t *pool){
  thread_info_t *thread;
  int i=0;
  for(i=0;i<pool->num;i++){
    thread = (thread_info_t*)(pool->threads+i);
    thread->state = THREAD_STATE_EXIT;
    pthread_join(thread->id,NULL);
  }
}
void thread_pool_destory(thread_pool_t *pool){
  thread_pool_t  *p   = pool;
  thread_worker_t *member = NULL;

  if(p->is_destroy)
    return ;
  p->is_destroy = true;
  pthread_cond_broadcast(&(p->queue_ready));
  thread_pool_wait(pool);
  free(p->threads);
  p->threads = NULL;
  /*销毁任务列表*/
  while(p->head){
    member = p->head;
    p->head = member->next;
    free(member);
  }
  /*销毁线程列表*/
  thread_info_t *tmp=NULL;
  while(p->threads){
    tmp = p->threads;
    p->threads = tmp->next;
    free(tmp);
  }

  pthread_mutex_destroy(&(p->queue_lock));
  pthread_cond_destroy(&(p->queue_ready));
  return ;
}
/*通过线程id,找到对应的线程*/
thread_info_t *get_thread_by_id(thread_pool_t *pool,pthread_t id){
  thread_info_t *thread=NULL;
  thread_info_t *p=pool->threads;
  while(p!=NULL){
    if(p->id==id)
      return p;
    p = p->next;
  }
  return NULL;
}

/*每个线程入口函数*/
void *thread_excute_route(void *arg){
  thread_worker_t *worker = NULL;
  thread_info_t  *thread = NULL;
  thread_pool_t*  p = (thread_pool_t*)arg;
  //printf("thread %lld create success\n",pthread_self());
  while(1){
    pthread_mutex_lock(&(p->queue_lock));

    /*获取当前线程的id*/
    pthread_t pthread_id = pthread_self();
    /*设置当前状态*/
    thread = get_thread_by_id(p,pthread_id);

    /*线程池被销毁,并且没有任务了*/
    if(p->is_destroy==true && p->queue_size ==0){
      pthread_mutex_unlock(&(p->queue_lock));
      thread->state = THREAD_STATE_EXIT;
      p->knum ++;
      p->rnum --;
      pthread_exit(NULL);
    }
    if(thread){
      thread->state = THREAD_STATE_TASK_WAITING; /*线程正在等待任务*/
    }
    /*线程池没有被销毁,没有任务到来就一直等待*/
    while(p->queue_size==0 && !p->is_destroy){
      pthread_cond_wait(&(p->queue_ready),&(p->queue_lock));
    }
    p->queue_size--;
    worker = p->head;
    p->head = worker->next;
    pthread_mutex_unlock(&(p->queue_lock));

    if(thread)
      thread->state = THREAD_STATE_TASK_PROCESSING; /*线程正在执行任务*/
    (*(worker->process))(worker->arg);
    if(thread)
      thread->state = THREAD_STATE_TASK_FINISHED;  /*任务执行完成*/
    free(worker);
    worker = NULL;
  }
}

/*拓展线程*/
void *thread_pool_is_need_extend(void *arg){
  thread_pool_t *p = (thread_pool_t *)arg;
  thread_pool_t *pool = p;
  /*判断是否需要增加线程,最终目的 线程:任务=1:2*/
  if(p->queue_size>100){
    int incr =0;
    if(((float)p->rnum/p->queue_size) < THREAD_BUSY_PERCENT ){
      incr = (p->queue_size*THREAD_BUSY_PERCENT) - p->rnum; /*计算需要增加线程个数*/
      int i=0;
      thread_info_t *tmp=NULL;
      thread_pool_t *p = pool;
      pthread_mutex_lock(&pool->queue_lock);
      if(p->queue_size<100){
        pthread_mutex_unlock(&pool->queue_lock);
        return ;
      }
      for(i=0;i<incr;i++){
        /*创建线程*/
        tmp= (struct thread_info_s*)malloc(sizeof(struct thread_info_s));
        if(tmp==NULL){
          continue;
        }else{
          tmp->next = p->threads;
          p->threads = tmp;
        }
        p->num ++;
        p->rnum ++;
        pthread_create(&(tmp->id),NULL,thread_excute_route,p);
        tmp->state = THREAD_STATE_RUN;
      }
      pthread_mutex_unlock(&pool->queue_lock);
    }
  }
  //pthread_cond_signal(&pool->extend_ready);
}
pthread_cond_t sum_ready;
/*恢复初始线程个数*/
void *thread_pool_is_need_recovery(void *arg){
  thread_pool_t *pool = (thread_pool_t *)arg;
  int i=0;
  thread_info_t *tmp = NULL,*prev=NULL,*p1=NULL;
  /*如果没有任务了,当前线程大于初始化的线程个数*/
  while(1){
    i=0;
    if(pool->queue_size==0 && pool->rnum > pool->init_num ){
      sleep(5);
      /*5s秒内还是这个状态的话就,销毁部分线程*/
      if(pool->queue_size==0 && pool->rnum > pool->init_num ){
        pthread_mutex_lock(&pool->queue_lock);
        tmp = pool->threads;
        while((pool->rnum != pool->init_num) && tmp){
          /*找到空闲的线程*/
          if(tmp->state != THREAD_STATE_TASK_PROCESSING){
            i++;
            if(prev)
              prev->next  = tmp->next;
            else
              pool->threads = tmp->next;
            pool->rnum --; /*正在运行的线程减一*/
            pool->knum ++; /*销毁的线程加一*/
            kill(tmp->id,SIGKILL); /*销毁线程*/
            p1 = tmp;
            tmp = tmp->next;
            free(p1);
            continue;
          }
          prev = tmp;
          tmp = tmp->next;
        }
        pthread_mutex_unlock(&pool->queue_lock);
        printf("5s内没有新任务销毁部分线程,销毁了 %d 个线程\n",i);
      }
    }
    sleep(5);
  }
}

/*打印一些信息的*/
void *display_thread(void *arg){
  thread_pool_t *p =(thread_pool_t *)arg;
  thread_info_t *thread = NULL;
  int i=0;
  while(1){
    printf("threads %d,running %d,killed %d\n",p->num,p->rnum,p->knum);  /*线程总数,正在跑的,已销毁的*/
    thread = p->threads;
    while(thread){
      printf("id=%ld,state=%s\n",thread->id,thread_state_map[thread->state]);
      thread = thread->next;
    }
    sleep(5);
  }
}

希望本文所述对大家学习C语言程序设计有所帮助。