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。
该文章会更新,欢迎大家批评指正。
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