linux多线程示例

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>

typedef void* (*fun)(void*);

fun fun1, fun2;

pthread_mutex_t pmu = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond;
pthread_t pid1, pid2;
int flag = 0;
int gnum = 0;
int gsub = 100;

void *  func1(void * para)
{
    int k = (int)para;
    printf("func1, ******
");
    while(gnum<=100)
    {   
        pthread_mutex_lock(&pmu);
        printf("gnum == %d", gnum);
        while(gnum==50)
        {   
            printf("suspend thread1 at gnum==50 !!! 
");
            pthread_cond_wait(&cond, &pmu);
            gnum++;
       }
        ++gnum;
        ++flag;
        ++k;
        //printf("flag = %d, k = %d
", flag, k);
        pthread_mutex_unlock(&pmu);
        printf("I am func1
");
    }
            pthread_exit((void*)0);

}

void * func2(void * para)
{
    int f = (int)para;
    printf("f == %d
", f);
    printf("pthread2 start running !
");
    void * ret = NULL;
    while(gsub>=0)
    {
        pthread_mutex_lock(&pmu);
        gsub--;
        printf("gsub= %d ", gsub);
        if(gsub == 20)
        {
            printf("now gsnb ==20, and send signal
");
            pthread_cond_signal(&cond);
        }
        ++flag;
       ++f;
        printf("flag = %d, f = %d
", flag, f);
        pthread_mutex_unlock(&pmu);
        printf("I am func2 
");
    }
    //pthread_join(pid1, &ret);
    pthread_exit((void*)0);
}

int main()
{
    int id = 0;
    void * ret = NULL;
    int key = 5;

    pthread_cond_init(&cond, NULL);  //属性设置NULL默认属性
    id = pthread_create(&pid1, NULL, func1, (void*)key);
    if(id != 0)
    {
        printf("pthread_create error !
");
        exit(0);
    }

    if(pthread_create(&pid2, NULL, func2, (void*)key))
    {
        printf("pthread_create error ! 
");
        exit(0);
    }
87     pthread_join(pid2, &ret);　　　　　　//等待pid2线程退出
88     pthread_join(pid1, &ret);　　　　　　//等待pid1线程退出

　　　　//pthread_detach(pid1);　　　　　　　　//主线程与pid1线程进行分离，一般用来实现异步返回
　　　　//pthread_detach(pid2);　　　　　　　　//同上
    pthread_exit((void*)0);
}

gcc test_thread.c -lpthread
./a.out

线程池实例代码：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <pthread.h>
#include <assert.h>

typedef struct worker
{
    //回调函数，任务运行时会调用此函数，也可以声明为其他形式；
    void * (*process)(void *arg);   //该函数返回值是任意类型的；参数也是任意类型的；`
    void *arg;  //回调函数的参数；
    struct worker *next;
}CThread_worker;

//线程池结构
typedef struct
{
    pthread_mutex_t queue_lock;     //互斥量
    pthread_cond_t queue_ready;     //条件变量

    //链表结构， 线程池中所有等待任务
    CThread_worker *queue_head;
    
    //是否销毁线程池
    int shutdown;
    pthread_t *threadid;
    
    //线程池中允许的活动线程数目；
    //线程池中允许的活动线程数目；
    int max_thread_num;
    //当前等待队列的任务数目;
    int  cur_queue_size;

}CThread_pool;

int pool_add_worker(void * (*process)(void *arg), void *arg);
void * thread_routine(void *arg);

static CThread_pool *pool = NULL;
void pool_init(int max_thread_num)
{
    pool = (CThread_pool*)malloc(sizeof(CThread_pool));

//初始化互斥量；
    pthread_mutex_init(&(pool->queue_lock), NULL);
//初始化条件变量
    pthread_cond_init(&(pool->queue_ready), NULL);

    pool->queue_head = NULL;
    
//最大线程数目
    pool->max_thread_num = max_thread_num;
//当前线程数目
    pool->cur_queue_size = 0;
    
    pool->shutdown = 0;
    pool->threadid = (pthread_t*)malloc(max_thread_num * sizeof(pthread_t));
    int i = 0;
    for(i=0; i<max_thread_num;i++)
    {
        pthread_create(&(pool->threadid[i]), NULL, thread_routine, NULL);
    }
}

//向线程池中加入任务
int pool_add_worker(void*(*process)(void *arg), void *arg)
{
    //构建一个新任务
    CThread_worker *newworker = (CThread_worker *)malloc(sizeof(CThread_worker));
    newworker->process = process;
    newworker->arg = arg;
    //别忘了置空
    newworker->next = NULL;

//加锁互斥量
    pthread_mutex_lock(&(pool->queue_lock));
    //将任务加入到等待队列中
    CThread_worker *member = pool->queue_head;
    if(member !=NULL)
    {
        while(member->next != NULL)
            member = member->next;
        member->next = newworker;
    }
    else
    {
        pool->queue_head = newworker;
    }
    
    assert(pool->queue_head != NULL);
    pool->cur_queue_size++;
    pthread_mutex_unlock(&(pool->queue_lock));
    
    //好了，等待队列中有任务了，唤醒一个等待线程；
    //     注意如果所有线程都在忙碌，这句没有任何作用
    pthread_cond_signal(&(pool->queue_ready));
    return 0;
}

/*销毁线程池，等待队列中的任务不会再被执行，
*但是正在运行的线程会一直 把任务运行完后 再退出；
*/

int pool_destroy()
{
    if(pool->shutdown)
        return -1;   //防止两次调用
    pool->shutdown = 1;
    
    //唤醒所有等待线程，线程池要销毁了 
    pthread_cond_broadcast(&(pool->queue_ready));
    
    //阻塞等待线程退出， 否则就成僵尸了
    int i;
    for(i=0; i<pool->max_thread_num; i++)
    {
        pthread_join(pool->threadid[i], NULL);
    }

    free(pool->threadid);

    //销毁等待队列
    CThread_worker *head = NULL;
    while(pool->queue_head != NULL)
    {
        head=pool->queue_head;
        pool->queue_head = pool->queue_head->next;
        free(head);
    }

    //条件变量和互斥量也别忘了销毁
    pthread_mutex_destroy(&(pool->queue_lock));
    pthread_cond_destroy(&(pool->queue_ready));

    free(pool);
     /*销毁后指针置空是个好习惯*/
    pool = NULL;
    return 0;
}

void* thread_routine(void *arg)
{
                   printf("start thread 0x%x
", pthread_self());
    while(1)
    {
        pthread_mutex_lock(&(pool->queue_lock));
/*如果等待队列为0并且不销毁线程池，则处于阻塞状态; 注意
 *pthread_cond_wait是一个原子操作，等待前会解锁，唤醒后会加锁*/
        while(pool->cur_queue_size == 0 && !pool->shutdown)
        {
            printf("thread 0x%x is waiting 
", pthread_self());
            pthread_cond_wait(&(pool->queue_ready), &(pool->queue_lock));
        }

        //线程池要销毁了；
        if(pool->shutdown)
        {
            //遇到break,continue,return等跳转语句，千万不要忘记先解锁*/
            pthread_mutex_unlock(&(pool->queue_lock));
            printf("thread 0x %x will exit 
", pthread_self());
            pthread_exit(NULL);
        }

        printf("thread 0x %x is starting to work 
", pthread_self());

        //使用断言
        assert(pool->cur_queue_size!= 0);
        assert(pool->queue_head!= NULL);

        //等待队列长度减去1，并取出链表中的头元素
        pool->cur_queue_size--;
       CThread_worker *worker = pool->queue_head;
        pool->queue_head = worker->next;
        pthread_mutex_unlock(&(pool->queue_lock));

        //调用回调函数，执行任务
        (*(worker->process))(worker->arg);
        free(worker);
        worker = NULL;
    }
    //这一句正常情况下是不可达的
    pthread_exit(NULL);
}

//test code
void *myprocess(void *arg)
{
    printf("threadid is 0x%x, working on task %d
", pthread_self(), *(int*)arg);
    sleep(1);  //休息一秒，延长任务的执行时间
    return NULL;
}

int main(int argc, char** argv)
{
    pool_init(3); /*线程池中最多三个活动线程*/

    //连续向线程池中放入10个任务；
    int *workingnum = (int*)malloc(sizeof(int)*10);
    int i;
    for(i=0; i< 10;i++)
    {
        workingnum[i] = i;
        pool_add_worker(myprocess, &workingnum[i]);
    }

    sleep(5);
//销毁线程池；  
    pool_destroy();
    free(workingnum);

    return 0;
}