线程池

线程池

线程池的思想

线程池的流程图

简单版本的线程池

主线程添加任务；子线程执行任务和销毁线程池

• threadpoolsimple.h

  #ifndef _THREADPOOL_H
  #define _THREADPOOL_H
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <sys/types.h>
  #include <unistd.h>
  #include <pthread.h>
  
  typedef struct _PoolTask
  {
      int tasknum;                  //模拟任务编号
      void *arg;                    //回调函数的参数
      void (*task_func)(void *arg); //任务的回调函数
  } PoolTask;
  
  typedef struct _ThreadPool
  {
      int max_job_num; //最大任务个数
      int job_num;     //实际任务个数
      PoolTask *tasks; //任务队列数组
      int job_push;    //入队位置
      int job_pop;     // 出队位置
  
      int thr_num;                   //线程池内线程个数
      pthread_t *threads;            //线程池内线程数组
      int shutdown;                  //是否关闭线程池
      pthread_mutex_t pool_lock;     //线程池的锁
      pthread_cond_t empty_task;     //任务队列为空的条件
      pthread_cond_t not_empty_task; //任务队列不为空的条件
  
  } ThreadPool;
  
  void create_threadpool(int thrnum, int maxtasknum); //创建线程池：thrnum 代表线程个数，maxtasknum 最大任务个数
  void destroy_threadpool(ThreadPool *pool);          //摧毁线程池
  void addtask(ThreadPool *pool);                     //添加任务到线程池
  void taskRun(void *arg);                            //任务回调函数
  
  #endif

• threadpoolsimple.c

  //简易版线程池
  #include "threadpoolsimple.h"
  
  ThreadPool *thrPool = NULL;
  
  int beginnum = 1000;
  
  void *thrRun(void *arg)
  {
      //printf("begin call %s-----\n",__FUNCTION__);
      ThreadPool *pool = (ThreadPool *)arg;
      int taskpos = 0; //任务位置
      PoolTask *task = (PoolTask *)malloc(sizeof(PoolTask));
  
      while (1)
      {
          //获取任务，先要尝试加锁
          pthread_mutex_lock(&thrPool->pool_lock);
  
          //无任务并且线程池不摧毁
          while (thrPool->job_num <= 0 && !thrPool->shutdown)
          {
              //如果没有任务，线程会阻塞
              pthread_cond_wait(&thrPool->not_empty_task, &thrPool->pool_lock);
          }
  
          if (thrPool->job_num)
          {
              //有任务需要处理
              taskpos = (thrPool->job_pop++) % thrPool->max_job_num;
              //printf("task out %d...tasknum===%d tid=%lu\n",taskpos,thrPool->tasks[taskpos].tasknum,pthread_self());
              //为什么要拷贝？避免任务被修改，生产者会添加任务
              memcpy(task, &thrPool->tasks[taskpos], sizeof(PoolTask));
              task->arg = task;
              thrPool->job_num--;
              //task = &thrPool->tasks[taskpos];
              pthread_cond_signal(&thrPool->empty_task); //通知主线程
          }
  
          if (thrPool->shutdown)
          {
              //代表要摧毁线程池，此时线程退出即可
              //pthread_detach(pthread_self());//临死前分家
              pthread_mutex_unlock(&thrPool->pool_lock);
              free(task);
              pthread_exit(NULL);
          }
  
          //释放锁
          pthread_mutex_unlock(&thrPool->pool_lock);
          task->task_func(task->arg); //执行回调函数
      }
  
      //printf("end call %s-----\n",__FUNCTION__);
  }
  
  //创建线程池
  void create_threadpool(int thrnum, int maxtasknum)
  {
      printf("begin call %s-----\n", __FUNCTION__);
      thrPool = (ThreadPool *)malloc(sizeof(ThreadPool));
  
      thrPool->thr_num = thrnum;
      thrPool->max_job_num = maxtasknum;
      thrPool->job_num = 0;  //初始化的任务个数为0
      thrPool->job_push = 0; //任务队列添加的位置
      thrPool->job_pop = 0;  //任务队列出队的位置
      thrPool->shutdown = 0; //是否摧毁线程池，1代表摧毁
  
      thrPool->tasks = (PoolTask *)malloc((sizeof(PoolTask) * maxtasknum)); //申请最大的任务队列
  
      //初始化锁和条件变量
      pthread_mutex_init(&thrPool->pool_lock, NULL);
      pthread_cond_init(&thrPool->empty_task, NULL);
      pthread_cond_init(&thrPool->not_empty_task, NULL);
  
      int i = 0;
      thrPool->threads = (pthread_t *)malloc(sizeof(pthread_t) * thrnum); //申请n个线程id的空间
  
      pthread_attr_t attr;
      pthread_attr_init(&attr);
      pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
      for (i = 0; i < thrnum; i++)
      {
          pthread_create(&thrPool->threads[i], &attr, thrRun, (void *)thrPool); //创建多个线程
      }
      //printf("end call %s-----\n",__FUNCTION__);
  }
  
  //摧毁线程池
  void destroy_threadpool(ThreadPool *pool)
  {
      pool->shutdown = 1;                            //开始自爆
      pthread_cond_broadcast(&pool->not_empty_task); //诱杀
  
      int i = 0;
      for (i = 0; i < pool->thr_num; i++)
      {
          pthread_join(pool->threads[i], NULL);
      }
  
      pthread_cond_destroy(&pool->not_empty_task);
      pthread_cond_destroy(&pool->empty_task);
      pthread_mutex_destroy(&pool->pool_lock);
  
      free(pool->tasks);
      free(pool->threads);
      free(pool);
  }
  
  //添加任务到线程池
  void addtask(ThreadPool *pool)
  {
      //printf("begin call %s-----\n",__FUNCTION__);
      pthread_mutex_lock(&pool->pool_lock);
  
      //实际任务总数大于最大任务个数则阻塞等待(等待任务被处理)
      while (pool->max_job_num <= pool->job_num)
      {
          pthread_cond_wait(&pool->empty_task, &pool->pool_lock);
      }
  
      int taskpos = (pool->job_push++) % pool->max_job_num;
      //printf("add task %d  tasknum===%d\n",taskpos,beginnum);
      pool->tasks[taskpos].tasknum = beginnum++;
      pool->tasks[taskpos].arg = (void *)&pool->tasks[taskpos];
      pool->tasks[taskpos].task_func = taskRun;
      pool->job_num++;
  
      pthread_mutex_unlock(&pool->pool_lock);
  
      pthread_cond_signal(&pool->not_empty_task); //通知子线程
      //printf("end call %s-----\n",__FUNCTION__);
  }
  
  //任务回调函数
  void taskRun(void *arg)
  {
      PoolTask *task = (PoolTask *)arg;
      int num = task->tasknum;
      printf("task %d is runing %lu\n", num, pthread_self());
  
      sleep(1);
      printf("task %d is done %lu\n", num, pthread_self());
  }
  
  int main()
  {
      create_threadpool(3, 20);
      int i = 0;
      for (i = 0; i < 50; i++)
      {
          addtask(thrPool); //模拟添加任务
      }
  
      sleep(20);
      destroy_threadpool(thrPool);
  
      return 0;
  }

复杂版本的线程池

主线程；子线程；管理线程

• threadpool.h

  #ifndef __THREADPOOL_H_
  #define __THREADPOOL_H_
  
  typedef struct threadpool_t threadpool_t;
  
  /**
   * @function threadpool_create
   * @descCreates a threadpool_t object.
   * @param thr_num  thread num
   * @param max_thr_num  max thread size
   * @param queue_max_size   size of the queue.
   * @return a newly created thread pool or NULL
   */
  threadpool_t *threadpool_create(int min_thr_num, int max_thr_num, int queue_max_size);
  
  /**
   * @function threadpool_add
   * @desc add a new task in the queue of a thread pool
   * @param pool     Thread pool to which add the task.
   * @param function Pointer to the function that will perform the task.
   * @param argument Argument to be passed to the function.
   * @return 0 if all goes well,else -1
   */
  int threadpool_add(threadpool_t *pool, void *(*function)(void *arg), void *arg);
  
  /**
   * @function threadpool_destroy
   * @desc Stops and destroys a thread pool.
   * @param pool  Thread pool to destroy.
   * @return 0 if destory success else -1
   */
  int threadpool_destroy(threadpool_t *pool);
  
  /**
   * @desc get the thread num
   * @pool pool threadpool
   * @return # of the thread
   */
  int threadpool_all_threadnum(threadpool_t *pool);
  
  /**
   * desc get the busy thread num
   * @param pool threadpool
   * return # of the busy thread
   */
  int threadpool_busy_threadnum(threadpool_t *pool);
  
  #endif

• threadpool.c

  #include <stdlib.h>
  #include <pthread.h>
  #include <unistd.h>
  #include <assert.h>
  #include <stdio.h>
  #include <string.h>
  #include <signal.h>
  #include <errno.h>
  #include "threadpool.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 /*每次创建和销毁线程的个数*/
  #define true 1
  #define false 0
  
  typedef struct
  {
      void *(*function)(void *); /* 函数指针，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 */
  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琐 -- 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; /* 任务队列里不为空时，通知等待任务的线程 */
  
      pthread_t *threads;            /* 存放线程池中每个线程tid的数组 */
      pthread_t adjust_tid;          /* 存管理线程tid */
      threadpool_task_t *task_queue; /* 任务队列(数组首地址) */
  
      int min_thr_num;       /* 线程池最小线程数 */
      int max_thr_num;       /* 线程池最大线程数 */
      int live_thr_num;      /* 当前存活线程个数 */
      int busy_thr_num;      /* 忙状态线程个数 */
      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 */
  };
  
  void *threadpool_thread(void *threadpool);
  
  void *adjust_thread(void *threadpool);
  
  int is_thread_alive(pthread_t tid);
  int threadpool_free(threadpool_t *pool);
  
  //threadpool_create(3,100,100);
  threadpool_t *threadpool_create(int min_thr_num, int max_thr_num, int queue_max_size)
  {
      int i;
      threadpool_t *pool = NULL;
      do
      {
          if ((pool = (threadpool_t *)malloc(sizeof(threadpool_t))) == NULL)
          {
              printf("malloc threadpool fail");
              break; /*跳出do while*/
          }
  
          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=最小线程数 */
          pool->wait_exit_thr_num = 0;
          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 == NULL)
          {
              printf("malloc threads fail");
              break;
          }
          memset(pool->threads, 0, sizeof(pthread_t) * max_thr_num);
  
          /* 队列开辟空间 */
          pool->task_queue = (threadpool_task_t *)malloc(sizeof(threadpool_task_t) * queue_max_size);
          if (pool->task_queue == NULL)
          {
              printf("malloc task_queue fail\n");
              break;
          }
  
          /* 初始化互斥琐、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 the lock or cond fail\n");
              break;
          }
  
          //启动工作线程
          pthread_attr_t attr;
          pthread_attr_init(&attr);
          pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
          for (i = 0; i < min_thr_num; i++)
          {
              pthread_create(&(pool->threads[i]), &attr, threadpool_thread, (void *)pool); /*pool指向当前线程池*/
              printf("start thread 0x%x...\n", (unsigned int)pool->threads[i]);
          }
  
          //创建管理者线程
          pthread_create(&(pool->adjust_tid), &attr, adjust_thread, (void *)pool);
  
          return pool;
      } while (0);
  
      /* 前面代码调用失败时，释放poll存储空间 */
      threadpool_free(pool);
  
      return NULL;
  }
  
  /* 向线程池中添加一个任务 */
  //threadpool_add(thp, process, (void*)&num[i]); /* 向线程池中添加任务 process: 小写---->大写*/
  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_cond_broadcast(&(pool->queue_not_empty));
          pthread_mutex_unlock(&(pool->lock));
          return 0;
      }
  
      /* 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)
      {
          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));
  
      return 0;
  }
  
  /* 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)
      {
          /* Lock must be taken to wait on conditional variable */
          /*刚创建出线程，等待任务队列里有任务，否则阻塞等待任务队列里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 wait 阻塞在条件变量上，若有任务，跳过该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)); //暂停到这
  
              /*清除指定数目的空闲线程，如果要结束的线程个数大于0，结束线程*/
              if (pool->wait_exit_thr_num > 0)
              {
                  pool->wait_exit_thr_num--;
  
                  /*如果线程池里线程个数大于最小值，可以结束当前线程*/
                  if (pool->live_thr_num > pool->min_thr_num)
                  {
                      printf("thread 0x%x is exiting\n", (unsigned int)pthread_self());
                      pool->live_thr_num--;
                      pthread_mutex_unlock(&(pool->lock));
                      //pthread_detach(pthread_self());
                      pthread_exit(NULL);
                  }
              }
          }
  
          /*如果指定了true，要关闭线程池里的每个线程，自行退出处理--销毁线程池*/
          if (pool->shutdown)
          {
              pthread_mutex_unlock(&(pool->lock));
              printf("thread 0x%x is exiting\n", (unsigned int)pthread_self());
              //pthread_detach(pthread_self());
              pthread_exit(NULL); /* 线程自行结束 */
          }
  
          /*从任务队列里获取任务, 是一个出队操作*/
          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; /* 出队，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，立即将线程池琐释放*/
          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)); /*忙状态线程数变量琐*/
          pool->busy_thr_num++;                        /*忙状态线程数+1*/
          pthread_mutex_unlock(&(pool->thread_counter));
  
          (*(task.function))(task.arg); /*执行回调函数任务*/
          //task.function(task.arg);
  
          /*任务结束处理*/
          printf("thread 0x%x end working\n", (unsigned int)pthread_self());
          pthread_mutex_lock(&(pool->thread_counter));
          pool->busy_thr_num--; /*处理掉一个任务，忙状态数线程数-1*/
          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 对线程池管理*/
  
          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; /* 忙着的线程数 */
          pthread_mutex_unlock(&(pool->thread_counter));
  
          /* 创建新线程：任务数大于最小线程池个数, 且存活的线程数少于最大线程个数时 如：30>=10 && 40<100*/
          if (queue_size >= MIN_WAIT_TASK_NUM && live_thr_num < pool->max_thr_num)
          {
              pthread_mutex_lock(&(pool->lock));
              int add = 0;
  
              /*一次增加 DEFAULT_THREAD 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[i] == 0 || !is_thread_alive(pool->threads[i]))
                  {
                      pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void *)pool);
                      add++;
                      pool->live_thr_num++;
                  }
              }
  
              pthread_mutex_unlock(&(pool->lock));
          }
  
          /* 销毁多余的空闲线程：忙线程X2小于存活的线程数，且存活的线程数大于最小线程数*/
          if ((busy_thr_num * 2) < live_thr_num && live_thr_num > pool->min_thr_num)
          {
              /* 一次销毁DEFAULT_THREAD个线程，随机10个 */
              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++)
              {
                  /* 通知处在空闲状态的线程, 他们会自行终止*/
                  pthread_cond_signal(&(pool->queue_not_empty));
              }
          }
      }
  
      return NULL;
  }
  
  int threadpool_destroy(threadpool_t *pool)
  {
      int i;
      if (pool == NULL)
      {
          return -1;
      }
      pool->shutdown = true;
  
      /*先销毁管理线程*/
      //pthread_join(pool->adjust_tid, NULL);
  
      for (i = 0; i < pool->live_thr_num; i++)
      {
          /*通知所有的空闲线程*/
          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;
  }
  
  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 threadpool_all_threadnum(threadpool_t *pool)
  {
      int all_threadnum = -1;
  
      pthread_mutex_lock(&(pool->lock));
      all_threadnum = pool->live_thr_num;
      pthread_mutex_unlock(&(pool->lock));
  
      return all_threadnum;
  }
  
  int threadpool_busy_threadnum(threadpool_t *pool)
  {
      int busy_threadnum = -1;
  
      pthread_mutex_lock(&(pool->thread_counter));
      busy_threadnum = pool->busy_thr_num;
      pthread_mutex_unlock(&(pool->thread_counter));
  
      return busy_threadnum;
  }
  
  int is_thread_alive(pthread_t tid)
  {
      int kill_rc = pthread_kill(tid, 0); //发0号信号，测试线程是否存活
      if (kill_rc == ESRCH)
      {
          return false;
      }
  
      return true;
  }
  
  /*测试*/
  
  #if 1
  /* 线程池中的线程，模拟处理业务 */
  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()
  {
      /*threadpool_t *threadpool_create(int min_thr_num, int max_thr_num, int queue_max_size);*/
      threadpool_t *thp = threadpool_create(3, 100, 100); /*创建线程池，池里最小3个线程，最大100，队列最大100*/
      printf("pool inited");
  
      //int *num = (int *)malloc(sizeof(int)*20);
      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); /* 等子线程完成任务 */
      threadpool_destroy(thp);
  
      return 0;
  }
  
  #endif