C实现线程池
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第一部分为头文件
1 #ifndef __THREADPOOL_H_ 2 #define __THREADPOOL_H_ 3 4 typedef struct threadpool_t threadpool_t; 5 6 /** 7 * @function threadpool_create 8 * @descCreates a threadpool_t object. 9 * @param thr_num thread num 10 * @param max_thr_num max thread size 11 * @param queue_max_size size of the queue. 12 * @return a newly created thread pool or NULL 13 */ 14 threadpool_t *threadpool_create(int min_thr_num, int max_thr_num, int queue_max_size); 15 16 /** 17 * @function threadpool_add 18 * @desc add a new task in the queue of a thread pool 19 * @param pool Thread pool to which add the task. 20 * @param function Pointer to the function that will perform the task. 21 * @param argument Argument to be passed to the function. 22 * @return 0 if all goes well,else -1 23 */ 24 int threadpool_add(threadpool_t *pool, void*(*function)(void *arg), void *arg); 25 26 /** 27 * @function threadpool_destroy 28 * @desc Stops and destroys a thread pool. 29 * @param pool Thread pool to destroy. 30 * @return 0 if destory success else -1 31 */ 32 int threadpool_destroy(threadpool_t *pool); 33 34 /** 35 * @desc get the thread num 36 * @pool pool threadpool 37 * @return # of the thread 38 */ 39 int threadpool_all_threadnum(threadpool_t *pool); 40 41 /** 42 * desc get the busy thread num 43 * @param pool threadpool 44 * return # of the busy thread 45 */ 46 int threadpool_busy_threadnum(threadpool_t *pool); 47 48 #endif
第二部分为自实现线程池代码（对libevent库进行一些精简，凸显逻辑）
1 #include <stdlib.h> 2 #include <pthread.h> 3 #include <unistd.h> 4 #include <assert.h> 5 #include <stdio.h> 6 #include <string.h> 7 #include <signal.h> 8 #include <errno.h> 9 #include "threadpool.h" 10 11 #define DEFAULT_TIME 10 /*10s检测一次*/ 12 #define MIN_WAIT_TASK_NUM 10 /*如果queue_size > MIN_WAIT_TASK_NUM 添加新的线程到线程池*/ 13 #define DEFAULT_THREAD_VARY 10 /*每次创建和销毁线程的个数*/ 14 #define true 1 15 #define false 0 16 17 typedef struct { 18 void *(*function)(void *); /* 函数指针，回调函数 */ 19 void *arg; /* 上面函数的参数 */ 20 } threadpool_task_t; /* 各子线程任务结构体 */ 21 22 /* 描述线程池相关信息 */ 23 struct threadpool_t { 24 pthread_mutex_t lock; /* 用于锁住本结构体 */ 25 pthread_mutex_t thread_counter; /* 记录忙状态线程个数de琐 -- busy_thr_num */ 26 27 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 */ 28 pthread_cond_t queue_not_empty; /* 任务队列里不为空时，通知等待任务的线程 */ 29 30 pthread_t *threads; /* 存放线程池中每个线程的tid。数组 */ 31 pthread_t adjust_tid; /* 存管理线程tid */ 32 threadpool_task_t *task_queue; /* 任务队列(数组首地址) */ 33 34 int min_thr_num; /* 线程池最小线程数 */ 35 int max_thr_num; /* 线程池最大线程数 */ 36 int live_thr_num; /* 当前存活线程个数 */ 37 int busy_thr_num; /* 忙状态线程个数 */ 38 int wait_exit_thr_num; /* 要销毁的线程个数 */ 39 40 int queue_front; /* task_queue队头下标 */ 41 int queue_rear; /* task_queue队尾下标 */ 42 int queue_size; /* task_queue队中实际任务数 */ 43 int queue_max_size; /* task_queue队列可容纳任务数上限 */ 44 45 int shutdown; /* 标志位，线程池使用状态，true或false */ 46 }; 47 48 void *threadpool_thread(void *threadpool); 49 50 void *adjust_thread(void *threadpool); 51 52 int is_thread_alive(pthread_t tid); 53 int threadpool_free(threadpool_t *pool); 54 55 //threadpool_create(3,100,100); 56 threadpool_t *threadpool_create(int min_thr_num, int max_thr_num, int queue_max_size) 57 { 58 int i; 59 threadpool_t *pool = NULL; 60 do { 61 if((pool = (threadpool_t *)malloc(sizeof(threadpool_t))) == NULL) { 62 printf("malloc threadpool fail"); 63 break; /*跳出do while*/ 64 } 65 66 pool->min_thr_num = min_thr_num; 67 pool->max_thr_num = max_thr_num; 68 pool->busy_thr_num = 0; 69 pool->live_thr_num = min_thr_num; /* 活着的线程数 初值=最小线程数 */ 70 pool->wait_exit_thr_num = 0; 71 pool->queue_size = 0; /* 有0个产品 */ 72 pool->queue_max_size = queue_max_size; 73 pool->queue_front = 0; 74 pool->queue_rear = 0; 75 pool->shutdown = false; /* 不关闭线程池 */ 76 77 /* 根据最大线程上限数， 给工作线程数组开辟空间, 并清零 */ 78 pool->threads = (pthread_t *)malloc(sizeof(pthread_t)*max_thr_num); 79 if (pool->threads == NULL) { 80 printf("malloc threads fail"); 81 break; 82 } 83 memset(pool->threads, 0, sizeof(pthread_t)*max_thr_num); 84 85 /* 队列开辟空间 */ 86 pool->task_queue = (threadpool_task_t *)malloc(sizeof(threadpool_task_t)*queue_max_size); 87 if (pool->task_queue == NULL) { 88 printf("malloc task_queue fail"); 89 break; 90 } 91 92 /* 初始化互斥琐、条件变量 */ 93 if (pthread_mutex_init(&(pool->lock), NULL) != 0 94 || pthread_mutex_init(&(pool->thread_counter), NULL) != 0 95 || pthread_cond_init(&(pool->queue_not_empty), NULL) != 0 96 || pthread_cond_init(&(pool->queue_not_full), NULL) != 0) 97 { 98 printf("init the lock or cond fail"); 99 break; 100 } 101 102 /* 启动 min_thr_num 个 work thread */ 103 for (i = 0; i < min_thr_num; i++) { 104 pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void *)pool);/*pool指向当前线程池*/ 105 printf("start thread 0x%x...\n", (unsigned int)pool->threads[i]); 106 } 107 pthread_create(&(pool->adjust_tid), NULL, adjust_thread, (void *)pool);/* 启动管理者线程 */ 108 109 return pool; 110 111 } while (0); 112 113 threadpool_free(pool); /* 前面代码调用失败时，释放poll存储空间 */ 114 115 return NULL; 116 } 117 118 /* 向线程池中 添加一个任务 */ 119 //threadpool_add(thp, process, (void*)&num[i]); /* 向线程池中添加任务 process: 小写---->大写*/ 120 121 int threadpool_add(threadpool_t *pool, void*(*function)(void *arg), void *arg) 122 { 123 pthread_mutex_lock(&(pool->lock)); 124 125 /* ==为真，队列已经满， 调wait阻塞 */ 126 while ((pool->queue_size == pool->queue_max_size) && (!pool->shutdown)) { 127 pthread_cond_wait(&(pool->queue_not_full), &(pool->lock)); 128 } 129 if (pool->shutdown) { 130 pthread_cond_broadcast(&(pool->queue_not_empty)); 131 pthread_mutex_unlock(&(pool->lock)); 132 return 0; 133 } 134 135 /* 清空 工作线程 调用的回调函数 的参数arg */ 136 if (pool->task_queue[pool->queue_rear].arg != NULL) { 137 pool->task_queue[pool->queue_rear].arg = NULL; 138 } 139 /*添加任务到任务队列里*/ 140 pool->task_queue[pool->queue_rear].function = function; 141 pool->task_queue[pool->queue_rear].arg = arg; 142 pool->queue_rear = (pool->queue_rear + 1) % pool->queue_max_size; /* 队尾指针移动, 模拟环形 */ 143 pool->queue_size++; 144 145 /*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*/ 146 pthread_cond_signal(&(pool->queue_not_empty)); 147 pthread_mutex_unlock(&(pool->lock)); 148 149 return 0; 150 } 151 152 /* 线程池中各个工作线程 */ 153 void *threadpool_thread(void *threadpool) 154 { 155 threadpool_t *pool = (threadpool_t *)threadpool; 156 threadpool_task_t task; 157 158 while (true) { 159 /* Lock must be taken to wait on conditional variable */ 160 /*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*/ 161 pthread_mutex_lock(&(pool->lock)); 162 163 /*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*/ 164 while ((pool->queue_size == 0) && (!pool->shutdown)) { 165 printf("thread 0x%x is waiting\n", (unsigned int)pthread_self()); 166 pthread_cond_wait(&(pool->queue_not_empty), &(pool->lock)); 167 168 /*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*/ 169 if (pool->wait_exit_thr_num > 0) { 170 pool->wait_exit_thr_num--; 171 172 /*如果线程池里线程个数大于最小值时可以结束当前线程*/ 173 if (pool->live_thr_num > pool->min_thr_num) { 174 printf("thread 0x%x is exiting\n", (unsigned int)pthread_self()); 175 pool->live_thr_num--; 176 pthread_mutex_unlock(&(pool->lock)); 177 178 pthread_exit(NULL); 179 } 180 } 181 } 182 183 /*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*/ 184 if (pool->shutdown) { 185 pthread_mutex_unlock(&(pool->lock)); 186 printf("thread 0x%x is exiting\n", (unsigned int)pthread_self()); 187 pthread_detach(pthread_self()); 188 pthread_exit(NULL); /* 线程自行结束 */ 189 } 190 191 /*从任务队列里获取任务, 是一个出队操作*/ 192 task.function = pool->task_queue[pool->queue_front].function; 193 task.arg = pool->task_queue[pool->queue_front].arg; 194 195 pool->queue_front = (pool->queue_front + 1) % pool->queue_max_size; /* 出队，模拟环形队列 */ 196 pool->queue_size--; 197 198 /*通知可以有新的任务添加进来*/ 199 pthread_cond_broadcast(&(pool->queue_not_full)); 200 201 /*任务取出后，立即将 线程池琐 释放*/ 202 pthread_mutex_unlock(&(pool->lock)); 203 204 /*执行任务*/ 205 printf("thread 0x%x start working\n", (unsigned int)pthread_self()); 206 pthread_mutex_lock(&(pool->thread_counter)); /*忙状态线程数变量琐*/ 207 pool->busy_thr_num++; /*忙状态线程数+1*/ 208 pthread_mutex_unlock(&(pool->thread_counter)); 209 210 (*(task.function))(task.arg); /*执行回调函数任务*/ 211 //task.function(task.arg); /*执行回调函数任务*/ 212 213 /*任务结束处理*/ 214 printf("thread 0x%x end working\n", (unsigned int)pthread_self()); 215 pthread_mutex_lock(&(pool->thread_counter)); 216 pool->busy_thr_num--; /*处理掉一个任务，忙状态数线程数-1*/ 217 pthread_mutex_unlock(&(pool->thread_counter)); 218 } 219 220 pthread_exit(NULL); 221 } 222 223 /* 管理线程 */ 224 void *adjust_thread(void *threadpool) 225 { 226 int i; 227 threadpool_t *pool = (threadpool_t *)threadpool; 228 while (!pool->shutdown) { 229 230 sleep(DEFAULT_TIME); /*定时 对线程池管理*/ 231 232 pthread_mutex_lock(&(pool->lock)); 233 int queue_size = pool->queue_size; /* 关注 任务数 */ 234 int live_thr_num = pool->live_thr_num; /* 存活 线程数 */ 235 pthread_mutex_unlock(&(pool->lock)); 236 237 pthread_mutex_lock(&(pool->thread_counter)); 238 int busy_thr_num = pool->busy_thr_num; /* 忙着的线程数 */ 239 pthread_mutex_unlock(&(pool->thread_counter)); 240 241 /* 创建新线程 算法： 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*/ 242 if (queue_size >= MIN_WAIT_TASK_NUM && live_thr_num < pool->max_thr_num) { 243 pthread_mutex_lock(&(pool->lock)); 244 int add = 0; 245 246 /*一次增加 DEFAULT_THREAD 个线程*/ 247 for (i = 0; i < pool->max_thr_num && add < DEFAULT_THREAD_VARY 248 && pool->live_thr_num < pool->max_thr_num; i++) { 249 if (pool->threads[i] == 0 || !is_thread_alive(pool->threads[i])) { 250 pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void *)pool); 251 add++; 252 pool->live_thr_num++; 253 } 254 } 255 256 pthread_mutex_unlock(&(pool->lock)); 257 } 258 259 /* 销毁多余的空闲线程 算法：忙线程X2 小于 存活的线程数 且 存活的线程数 大于 最小线程数时*/ 260 if ((busy_thr_num * 2) < live_thr_num && live_thr_num > pool->min_thr_num) { 261 262 /* 一次销毁DEFAULT_THREAD个线程, 隨機10個即可 */ 263 pthread_mutex_lock(&(pool->lock)); 264 pool->wait_exit_thr_num = DEFAULT_THREAD_VARY; /* 要销毁的线程数 设置为10 */ 265 pthread_mutex_unlock(&(pool->lock)); 266 267 for (i = 0; i < DEFAULT_THREAD_VARY; i++) { 268 /* 通知处在空闲状态的线程, 他们会自行终止*/ 269 pthread_cond_signal(&(pool->queue_not_empty)); 270 } 271 } 272 } 273 274 return NULL; 275 } 276 277 int threadpool_destroy(threadpool_t *pool) 278 { 279 int i; 280 if (pool == NULL) { 281 return -1; 282 } 283 pool->shutdown = true; 284 285 /*先销毁管理线程*/ 286 pthread_join(pool->adjust_tid, NULL); 287 288 for (i = 0; i < pool->live_thr_num; i++) { 289 /*通知所有的空闲线程*/ 290 pthread_cond_broadcast(&(pool->queue_not_empty)); 291 } 292 for (i = 0; i < pool->live_thr_num; i++) { 293 pthread_join(pool->threads[i], NULL); 294 } 295 threadpool_free(pool); 296 297 return 0; 298 } 299 300 int threadpool_free(threadpool_t *pool) 301 { 302 if (pool == NULL) { 303 return -1; 304 } 305 306 if (pool->task_queue) { 307 free(pool->task_queue); 308 } 309 if (pool->threads) { 310 free(pool->threads); 311 pthread_mutex_lock(&(pool->lock)); 312 pthread_mutex_destroy(&(pool->lock)); 313 pthread_mutex_lock(&(pool->thread_counter)); 314 pthread_mutex_destroy(&(pool->thread_counter)); 315 pthread_cond_destroy(&(pool->queue_not_empty)); 316 pthread_cond_destroy(&(pool->queue_not_full)); 317 } 318 free(pool); 319 pool = NULL; 320 321 return 0; 322 } 323 324 int threadpool_all_threadnum(threadpool_t *pool) 325 { 326 int all_threadnum = -1; 327 pthread_mutex_lock(&(pool->lock)); 328 all_threadnum = pool->live_thr_num; 329 pthread_mutex_unlock(&(pool->lock)); 330 return all_threadnum; 331 } 332 333 int threadpool_busy_threadnum(threadpool_t *pool) 334 { 335 int busy_threadnum = -1; 336 pthread_mutex_lock(&(pool->thread_counter)); 337 busy_threadnum = pool->busy_thr_num; 338 pthread_mutex_unlock(&(pool->thread_counter)); 339 return busy_threadnum; 340 } 341 342 int is_thread_alive(pthread_t tid) 343 { 344 int kill_rc = pthread_kill(tid, 0); //发0号信号，测试线程是否存活 345 if (kill_rc == ESRCH) { 346 return false; 347 } 348 349 return true; 350 } 351 352 /*测试*/ 353 354 #if 1 355 /* 线程池中的线程，模拟处理业务 */ 356 void *process(void *arg) 357 { 358 printf("thread 0x%x working on task %d\n ",(unsigned int)pthread_self(),(int)arg); 359 sleep(1); //小---大写 360 printf("task %d is end\n",(int)arg); 361 362 return NULL; 363 } 364 365 int main(void) 366 { 367 /*threadpool_t *threadpool_create(int min_thr_num, int max_thr_num, int queue_max_size);*/ 368 369 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*/ 370 printf("pool inited"); 371 372 //int *num = (int *)malloc(sizeof(int)*20); 373 int num[20], i; 374 for (i = 0; i < 20; i++) { 375 num[i]=i; 376 printf("add task %d\n",i); 377 threadpool_add(thp, process, (void*)&num[i]); /* 向线程池中添加任务 */ 378 } 379 sleep(10); /* 等子线程完成任务 */ 380 threadpool_destroy(thp); 381 382 return 0; 383 } 384 385 #endif
=======================
线程池的相关信息：
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de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的tid。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 */
};
============================================
查看这段代码的步骤及代码的相关逻辑步骤
1. 大结构体， threadpool_task_t;结构体
2. main
threadpool_create 创建线程池。
for产出任务
threadpool_add 添加任务。
销毁线程池。
3. threadpool_create()
4. threadpool_thread()
跟踪到pthread_cond_wait（）；阻塞
5. threadpool_add（）
跟踪到pthread_cond_signal（）； 会到4步中 pthread_cond_wait（）继续向后。
6. adjust_thread（）
添加10个线程
移除10个线程 ---pthread_exit();
7. threadpool_destroy（）
销毁线程池。 ---pthread_exit();
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