Question

typedef struct 
  {
  int count;
  pthread_mutex_t mutex;
  } Counter;

typedef struct 
{
  int countA;
  int countB;
  pthread_mutex_t mutex;
} Counter2;

void* TFa();
void* TFb();

Counter *cA;
Counter *cB;
Counter2 *c;

sem_t *S1, *S2;


int main(int argc, char **argv)
{

    S1 = (sem_t *) malloc(sizeof(sem_t));
    S2 = (sem_t *) malloc(sizeof(sem_t));
    sem_init(S1,0,1);
    sem_init(S2,0,1);
    int n = atoi(argv[1]);
    pthread_t *t1;
    pthread_t *t2;
    cA= (Counter *) malloc (sizeof(Counter));
    cB= (Counter *) malloc (sizeof(Counter));
    c= (Counter2 *) malloc (sizeof(Counter2));
    cA->count =0;
    cB->count =0;
    c-> countA =0;
    c-> countB =0;
    pthread_mutex_init(&cA->mutex, NULL);
    pthread_mutex_init(&cB->mutex, NULL);
    pthread_mutex_init(&c->mutex, NULL);
    t1 = malloc(sizeof(pthread_t)*n);
    t2 = malloc((sizeof(pthread_t)*2*n));

    for(int i=0; i<n; i++){
        pthread_create(&t1[i], NULL, TFa, NULL);
    for(int i=0; i<n; i++){
        pthread_create(&t2[i], NULL, TFb, NULL);

    pthread_exit(NULL);
    return 0;
}

void* TFa()
{

    pthread_mutex_lock(&cA ->mutex);
    int num = cA->count;
    cA->count++;
    pthread_mutex_unlock(&cA->mutex);
    pthread_mutex_lock (&c->mutex);
    if(c->countA ==0 && c->countB ==2 )
    {
        printf("A%d 1n", num);
        c->countA =0;
        c->countB=0;
        sem_post(S1);
        pthread_mutex_unlock(&c->mutex);


    }
    else if(c->countA ==0 && c->countB <2)
    {   
        printf("A%d \n",num);
        c->countA ++;
        pthread_mutex_unlock(&c->mutex);
    }
    else
    {
        pthread_mutex_unlock(&c->mutex);
        sem_wait(S1);
        pthread_mutex_lock(&c->mutex);
        printf("A%d \n", num);
        c->countA++;
        pthread_mutex_unlock(&c->mutex);

    }
    pthread_exit(NULL);

}

void* TFb()
{
    pthread_mutex_lock(&cB->mutex);
    int num = cB->count;
    cB->count++;
    pthread_mutex_unlock(&cB->mutex);
    pthread_mutex_lock(&c->mutex);
    if(c->countA ==1 && c->countB ==1)
    {
        printf("B%d \n", num);
        c->countA =0;
        c->countB=0;
        sem_post(S2);
        sem_post(S2);
        pthread_mutex_unlock(&c->mutex);
    }
    else if(c->countA <2 && c->countB ==0)
    {
        printf("B%d \n", num);
        c->countB++;
        pthread_mutex_unlock(&c->mutex);
    }
    else
    {
        phtread_mutex_unlock(&c->mutex);
        sem_wait(S2);
        pthread_mutex_lock(&c->mutex);
        printf("B%d \n", num);
        c->countB++;
        pthread_mutex_unlock(&c->mutex);
    }
    pthread_exit(NULL);
}

我对这个小程序有疑问：

使用生成n的Pthreads在C语言中实现并发程序线程th_A执行代码A，2 * n个线程th_B执行代码B. 主线程从命令行获取参数n，并在没有的情况下终止等待它创建的线程的终止。两个线程只是打印相应的字符，然后是它们的顺序创建号（th_A从0到n-1，th_B从0到2 * n-1）。两个B和一个A字符打印后，无论哪个顺序，最后一个打印线程必须打印'\ n'字符。

但它没有编译，我不理解方式。你有一些提示吗？

Answer 1

    for(int i=0; i<n; i++){
        pthread_create(&t1[i], NULL, TFa, NULL);
    for(int i=0; i<n; i++){
        pthread_create(&t2[i], NULL, TFb, NULL);

这些{没有匹配的}。

    phtread_mutex_unlock(&c->mutex);

您写了p ht 而不是pthread。

有了这两个修复程序和缺少的#include，它就会编译。

与信号量同步

1 个答案: