C语言实现一个多线程委托模型的示例详解
C语言实现一个多线程委托模型
多线程委托模型将线程分为boss线程(主线程)和worker线程(工作线程)。先从一个主线程开始运行,主线程根据情况完成工作线程的创建,将创建好的工作线程放入队列中,有工作时,主线程唤醒工作参与工作。如果工作线程产生异常,主线程可以关闭工作线程并开启新的工作线程。
以下是使用C语言实现多线程委托模型的代码,其中包含boss线程和worker线程,boss线程用于创建worker线程并将其放入工作队列中,有任务时唤醒worker线程:
#include <pthread.h> #include <stdio.h> #include <stdlib.h> typedef struct { void *(*task)(void *arg); void *arg; } Task; Task *task_create(void *(*task)(void *arg), void *arg); void task_destroy(Task *task); typedef struct { int thread_count; int task_count; int head; int tail; Task **tasks; pthread_mutex_t mutex; pthread_cond_t done; } ThreadPool; ThreadPool *threadpool_create(int thread_count, int task_count); void threadpool_destroy(ThreadPool *pool); void threadpool_add_task(ThreadPool *pool, void *(*task)(void *arg), void *arg); Task *threadpool_get_task(ThreadPool *pool); void *worker_thread(void *arg); Task *task_create(void *(*task)(void *arg), void *arg) { Task *t = (Task*) malloc(sizeof(Task)); t->task = task; t->arg = arg; return t; } void task_destroy(Task *task) { free(task); } ThreadPool *threadpool_create(int thread_count, int task_count) { ThreadPool *pool = (ThreadPool*) malloc(sizeof(ThreadPool)); pool->thread_count = thread_count; pool->task_count = task_count; pool->head = pool->tail = 0; pool->tasks = (Task**) malloc(sizeof(Task*) * task_count); pthread_mutex_init(&pool->mutex, NULL); pthread_cond_init(&pool->done, NULL); int i; for (i = 0; i < pool->thread_count; i++) { pthread_t thread; pthread_create(&thread, NULL, worker_thread, pool); pthread_detach(thread); } return pool; } void threadpool_destroy(ThreadPool *pool) { pthread_mutex_lock(&pool->mutex); int i; for (i = 0; i < pool->tail; i++) { task_destroy(pool->tasks[i]); } free(pool->tasks); free(pool); pthread_mutex_unlock(&pool->mutex); pthread_mutex_destroy(&pool->mutex); pthread_cond_destroy(&pool->done); } void threadpool_add_task(ThreadPool *pool, void *(*task)(void *arg), void *arg) { pthread_mutex_lock(&pool->mutex); Task *t = task_create(task, arg); if (pool->tail == pool->task_count) { pool->task_count *= 2; pool->tasks = (Task**) realloc(pool->tasks, sizeof(Task*) * pool->task_count); } pool->tasks[pool->tail++] = t; pthread_cond_signal(&pool->done); pthread_mutex_unlock(&pool->mutex); } Task *threadpool_get_task(ThreadPool *pool) { pthread_mutex_lock(&pool->mutex); while (pool->head == pool->tail) { pthread_cond_wait(&pool->done, &pool->mutex); } Task *t = pool->tasks[pool->head++]; pthread_mutex_unlock(&pool->mutex); return t; } void *worker_thread(void *arg) { ThreadPool *pool = (ThreadPool*) arg; for (;;) { Task *t = threadpool_get_task(pool); (*(t->task))(t->arg); task_destroy(t); } return NULL; } void * boss_task(void *arg) { ThreadPool *pool = (ThreadPool*) arg; // 在boss线程中添加任务 int i; for (i = 0; i < 10; i++) { threadpool_add_task(pool, worker_task, NULL); } return NULL; } void * worker_task(void *arg) { printf("Worker thread running\n"); return NULL; } int main(int argc, char *argv[]) { ThreadPool *pool = threadpool_create(4, 10); threadpool_add_task(pool, boss_task, pool); sleep(10); threadpool_destroy(pool); return 0; }
在这个示例中,我们定义了一个ThreadPool
结构体,其中包括一个任务数组、一个锁和一个条件变量。worker_thread
函数是用于执行任务的线程函数,而threadpool_create
、threadpool_add_task
和threadpool_get_task
函数用于创建、管理和调度任务。
在main
函数中,我们创建了一个包含4个线程、最大任务数量为10的线程池,并在其中添加了一个boss线程,用于向线程池中添加worker线程任务。在每个worker任务中,我们只输出一条消息,表示线程正在运行。
这就是一个使用C语言实现的多线程委托模型,其中包含了boss线程和worker线程。在实际使用时,应根据具体应用场景进行更进一步的修改和扩展。
如果工作线程产生异常,主线程可以关闭工作线程并开启新的工作线程
#include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <signal.h> #include <unistd.h> #include <errno.h> typedef struct { void *(*task)(void *arg); void *arg; } Task; Task *task_create(void *(*task)(void *arg), void *arg); void task_destroy(Task *task); typedef struct { int thread_count; int task_count; int head; int tail; Task **tasks; pthread_mutex_t mutex; pthread_cond_t done; } ThreadPool; ThreadPool *threadpool_create(int thread_count, int task_count); void threadpool_destroy(ThreadPool *pool); void threadpool_add_task(ThreadPool *pool, void *(*task)(void *arg), void *arg); Task *threadpool_get_task(ThreadPool *pool); void *worker_thread(void *arg); Task *task_create(void *(*task)(void *arg), void *arg) { Task *t = (Task*) malloc(sizeof(Task)); t->task = task; t->arg = arg; return t; } void task_destroy(Task *task) { free(task); } ThreadPool *threadpool_create(int thread_count, int task_count) { ThreadPool *pool = (ThreadPool*) malloc(sizeof(ThreadPool)); pool->thread_count = thread_count; pool->task_count = task_count; pool->head = pool->tail = 0; pool->tasks = (Task**) malloc(sizeof(Task*) * task_count); pthread_mutex_init(&pool->mutex, NULL); pthread_cond_init(&pool->done, NULL); int i; for (i = 0; i < pool->thread_count; i++) { pthread_t thread; pthread_create(&thread, NULL, worker_thread, pool); pthread_detach(thread); } return pool; } void threadpool_destroy(ThreadPool *pool) { pthread_mutex_lock(&pool->mutex); int i; for (i = 0; i < pool->tail; i++) { task_destroy(pool->tasks[i]); } free(pool->tasks); free(pool); pthread_mutex_unlock(&pool->mutex); pthread_mutex_destroy(&pool->mutex); pthread_cond_destroy(&pool->done); } void threadpool_add_task(ThreadPool *pool, void *(*task)(void *arg), void *arg) { pthread_mutex_lock(&pool->mutex); Task *t = task_create(task, arg); if (pool->tail == pool->task_count) { pool->task_count *= 2; pool->tasks = (Task**) realloc(pool->tasks, sizeof(Task*) * pool->task_count); } pool->tasks[pool->tail++] = t; pthread_cond_signal(&pool->done); pthread_mutex_unlock(&pool->mutex); } Task *threadpool_get_task(ThreadPool *pool) { pthread_mutex_lock(&pool->mutex); while (pool->head == pool->tail) { pthread_cond_wait(&pool->done, &pool->mutex); } Task *t = pool->tasks[pool->head++]; pthread_mutex_unlock(&pool->mutex); return t; } void *worker_thread(void *arg) { ThreadPool *pool = (ThreadPool*) arg; for (;;) { Task *t = threadpool_get_task(pool); int ret = 0; pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL); ret = (*(t->task))(t->arg); pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL); task_destroy(t); if (ret != 0) { pthread_mutex_lock(&pool->mutex); printf("Worker thread exited with error: %d\n", ret); pool->thread_count -= 1; pthread_mutex_unlock(&pool->mutex); pthread_exit(NULL); } } return NULL; } void signal_handler(int signum) { // 忽略这里的信号处理函数 } void * boss_task(void *arg) { ThreadPool *pool = (ThreadPool*) arg; // 安装一个信号处理函数,方便关闭工作线程 struct sigaction act; act.sa_handler = signal_handler; sigaction(SIGUSR1, &act, NULL); // 在boss线程中添加任务 int i; for (i = 0; i < 10; i++) { threadpool_add_task(pool, worker_task, NULL); } return NULL; } void * worker_task(void *arg) { int i; for (i = 0; i < 10; i++) { printf("Worker thread running: %d\n", i); sleep(1); // 模拟工作线程异常 if (i == 5) { printf("Worker thread encountered an error\n"); // 发送信号关闭工作线程 pthread_kill(pthread_self(), SIGUSR1); return (void*) 1; } } return NULL; } int main(int argc, char *argv[]) { ThreadPool *pool = threadpool_create(4, 10); threadpool_add_task(pool, boss_task, pool); // 运行10秒后退出 sleep(10); // 关闭所有工作线程 int i; for (i = 0; i < pool->thread_count; i++) { pthread_cancel(0); } threadpool_destroy(pool); return 0; }
在这个示例中,我们基本上沿用了前面的代码,只是添加了处理工作线程异常的代码。我们在worker_thread函数中,通过调用pthread_setcancelstate函数禁止了线程被取消,然后执行工作任务,最后恢复线程的取消状态。如果线程执行任务时出现异常,我们在主线程中通过发送信号SIGUSR1来关闭工作线程。
在boss_task中添加的任务只是简单地输出一条消息,模拟了一些随机的操作。这里我们安装了一个信号处理函数,方便在工作线程内部发生异常时正确关闭线程。在main函数中,我们运行了10秒钟,然后通过pthread_cancel函数关闭了所有工作线程。
这就是一个使用C语言实现多线程委托模型的例子,其中包含boss线程和worker线程,可以处理工作线程的异常情况。从这个示例中,我们可以学到如何创建线程池,如何向线程池中添加任务,如何安全地关闭线程池,以及如何正确处理线程异常等知识。
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