http://www.linuxidc.com/Linux/2013-01/77619.htm

有時我們會需要大量線程來處理一些相互獨立的任務(wù)，為了避免頻繁的申請釋放線程所帶來的開銷，我們可以使用線程池。下面是一個C語言實現(xiàn)的簡單的線程池。

頭文件：

1: #ifndef THREAD_POOL_H__ 2: #define THREAD_POOL_H__ 3: 4: #include <pthread.h> 5: 6: /* 要執(zhí)行的任務(wù)鏈表 */ 7: typedef struct tpool_work { 8: void* (*routine)(void*); /* 任務(wù)函數(shù) */ 9: void *arg; /* 傳入任務(wù)函數(shù)的參數(shù) */ 10: struct tpool_work *next; 11: }tpool_work_t; 12: 13: typedef struct tpool { 14: int shutdown; /* 線程池是否銷毀 */ 15: int max_thr_num; /* 最大線程數(shù) */ 16: pthread_t *thr_id; /* 線程ID數(shù)組 */ 17: tpool_work_t *queue_head; /* 線程鏈表 */ 18: pthread_mutex_t queue_lock; 19: pthread_cond_t queue_ready; 20: }tpool_t; 21: 22: /* 23: * @brief 創(chuàng)建線程池 24: * @param max_thr_num 最大線程數(shù) 25: * @return 0: 成功 其他: 失敗 26: */ 27: int 28: tpool_create(int max_thr_num); 29: 30: /* 31: * @brief 銷毀線程池 32: */ 33: void 34: tpool_destroy(); 35: 36: /* 37: * @brief 向線程池中添加任務(wù) 38: * @param routine 任務(wù)函數(shù)指針 39: * @param arg 任務(wù)函數(shù)參數(shù) 40: * @return 0: 成功 其他:失敗 41: */ 42: int 43: tpool_add_work(void*(*routine)(void*), void *arg); 44: 45: #endif

實現(xiàn):

1: #include <unistd.h> 2: #include <stdlib.h> 3: #include <errno.h> 4: #include <string.h> 5: #include <stdio.h> 6: 7: #include "tpool.h" 8: 9: static tpool_t *tpool = NULL; 10: 11: /* 工作者線程函數(shù), 從任務(wù)鏈表中取出任務(wù)并執(zhí)行 */ 12: static void* 13: thread_routine(void *arg) 14: { 15: tpool_work_t *work; 16: 17: while(1) { 18: /* 如果線程池沒有被銷毀且沒有任務(wù)要執(zhí)行，則等待 */ 19: pthread_mutex_lock(&tpool->queue_lock); 20: while(!tpool->queue_head && !tpool->shutdown) { 21: pthread_cond_wait(&tpool->queue_ready, &tpool->queue_lock); 22: } 23: if (tpool->shutdown) { 24: pthread_mutex_unlock(&tpool->queue_lock); 25: pthread_exit(NULL); 26: } 27: work = tpool->queue_head; 28: tpool->queue_head = tpool->queue_head->next; 29: pthread_mutex_unlock(&tpool->queue_lock); 30: 31: work->routine(work->arg); 32: free(work); 33: } 34: 35: return NULL; 36: } 37: 38: /* 39: * 創(chuàng)建線程池 40: */ 41: int 42: tpool_create(int max_thr_num) 43: { 44: int i; 45: 46: tpool = calloc(1, sizeof(tpool_t)); 47: if (!tpool) { 48: printf("%s: calloc failed\n", __FUNCTION__); 49: exit(1); 50: } 51: 52: /* 初始化 */ 53: tpool->max_thr_num = max_thr_num; 54: tpool->shutdown = 0; 55: tpool->queue_head = NULL; 56: if (pthread_mutex_init(&tpool->queue_lock, NULL) !=0) { 57: printf("%s: pthread_mutex_init failed, errno:%d, error:%s\n", 58: __FUNCTION__, errno, strerror(errno)); 59: exit(1); 60: } 61: if (pthread_cond_init(&tpool->queue_ready, NULL) !=0 ) { 62: printf("%s: pthread_cond_init failed, errno:%d, error:%s\n", 63: __FUNCTION__, errno, strerror(errno)); 64: exit(1); 65: } 66: 67: /* 創(chuàng)建工作者線程 */ 68: tpool->thr_id = calloc(max_thr_num, sizeof(pthread_t)); 69: if (!tpool->thr_id) { 70: printf("%s: calloc failed\n", __FUNCTION__); 71: exit(1); 72: } 73: for (i = 0; i < max_thr_num; ++i) { 74: if (pthread_create(&tpool->thr_id[i], NULL, thread_routine, NULL) != 0){ 75: printf("%s:pthread_create failed, errno:%d, error:%s\n", __FUNCTION__, 76: errno, strerror(errno)); 77: exit(1); 78: } 79: 80: } 81: 82: return 0; 83: } 84: 85: /* 銷毀線程池 */ 86: void 87: tpool_destroy() 88: { 89: int i; 90: tpool_work_t *member; 91: 92: if (tpool->shutdown) { 93: return; 94: } 95: tpool->shutdown = 1; 96: 97: /* 通知所有正在等待的線程 */ 98: pthread_mutex_lock(&tpool->queue_lock); 99: pthread_cond_broadcast(&tpool->queue_ready); 100: pthread_mutex_unlock(&tpool->queue_lock); 101: for (i = 0; i < tpool->max_thr_num; ++i) { 102: pthread_join(tpool->thr_id[i], NULL); 103: } 104: free(tpool->thr_id); 105: 106: while(tpool->queue_head) { 107: member = tpool->queue_head; 108: tpool->queue_head = tpool->queue_head->next; 109: free(member); 110: } 111: 112: pthread_mutex_destroy(&tpool->queue_lock); 113: pthread_cond_destroy(&tpool->queue_ready); 114: 115: free(tpool); 116: } 117: 118: /* 向線程池添加任務(wù) */ 119: int 120: tpool_add_work(void*(*routine)(void*), void *arg) 121: { 122: tpool_work_t *work, *member; 123: 124: if (!routine){ 125: printf("%s:Invalid argument\n", __FUNCTION__); 126: return -1; 127: } 128: 129: work = malloc(sizeof(tpool_work_t)); 130: if (!work) { 131: printf("%s:malloc failed\n", __FUNCTION__); 132: return -1; 133: } 134: work->routine = routine; 135: work->arg = arg; 136: work->next = NULL; 137: 138: pthread_mutex_lock(&tpool->queue_lock); 139: member = tpool->queue_head; 140: if (!member) { 141: tpool->queue_head = work; 142: } else { 143: while(member->next) { 144: member = member->next; 145: } 146: member->next = work; 147: } 148: /* 通知工作者線程，有新任務(wù)添加 */ 149: pthread_cond_signal(&tpool->queue_ready); 150: pthread_mutex_unlock(&tpool->queue_lock); 151: 152: return 0; 153: } 154: 155:

測試代碼:

1: #include <unistd.h> 2: #include <stdio.h> 3: #include <stdlib.h> 4: #include "tpool.h" 5: 6: void *func(void *arg) 7: { 8: printf("thread %d\n", (int)arg); 9: return NULL; 10: } 11: 12: int 13: main(int arg, char **argv) 14: { 15: if (tpool_create(5) != 0) { 16: printf("tpool_create failed\n"); 17: exit(1); 18: } 19: 20: int i; 21: for (i = 0; i < 10; ++i) { 22: tpool_add_work(func, (void*)i); 23: } 24: sleep(2); 25: tpool_destroy(); 26: return 0; 27: }

這個實現(xiàn)是在調(diào)用tpool_destroy之后，僅將當(dāng)前正在執(zhí)行的任務(wù)完成之后就會退出，我們也可以修改代碼使得線程池在執(zhí)行完任務(wù)鏈表中所有任務(wù)后再退出。

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