pthread_join中的分段错误

Question

因此,当我运行我的代码时,我在pthread_join上遇到了分段错误.在我的pthread_join之后有一个没有运行的print语句.有谁知道为什么？你能给我一些关于如何解决这个问题的提示或想法吗？

输出打印出矩阵的所有行号,直到结束,然后它离开matrixCalc函数并在"创建线程后"打印.当我为1个线程添加一个参数时会发生这种情况.

我在这里包含了我的一小部分代码:

int main(int argc, char*argv[]) 
{
  //takes in number of threads as 1st arg
  pthread_attr_init(&attr);
  //initialize matrix here

  //passes num of threads through matrixcalc
  for(i = 0; i < numberOfThreads; i++)
    {
      threadCount++;
      pthread_create(&tid, &attr, matrixCalc(threadCount), NULL);  
    }
  printf("after threads are created\n");
  pthread_join(tid, NULL);  
  printf("after join\n");
  exit(0);
  return 0;
}

这是矩阵计算功能:

    void *matrixCalc(threadCount) 
{
  int i, j, sum, tempNum, currentRow;
  currentRow = threadCount;
  sum=0;

  while(currentRow < 1200)
    {
      //cycles through the column j for matrix B
      for(j=0; j<500; j++)
        {
          //cycles through the diff i values for the set row in matrix A and column in matrix B
          for(i=0; i<1000; i++)
            {
              //Matrix A set i value is at threadcount-1
              //Matrix B i value = j
              //Matrix B j value = i
              //Multiply together and add to sum
              tempNum = (matrixA[currentRow-1][i])*(matrixB[i][j]);
              sum = sum+tempNum;
            }
          //Set Matrix C at i value = currentRow and jvalue = i to sum
          matrixC[currentRow-1][j] = sum;
          //printf("%d\n", matrixC[currentRow-1][i]);
        }
        //increase threadcount by number of threads 
        //until you hit max/past max val
        currentRow = currentRow + nThreads;
        //printf("%d\n", currentRow);
    }
    return NULL;

}

Answer 1

在调用时,pthread_create()您需要传递类型函数的地址void *(*)(void *).代码所做的是在那里调用一个函数,以便将结果传递给它pthread_create().

改变这一行

pthread_create(&tid, &attr, matrixCalc(threadCount), NULL);  

成为

pthread_create(&tid, &attr, matrixCalc, NULL);  

要么

pthread_create(&tid, &attr, &matrixCalc, NULL);  

实际上是一样的.

如上所述,线程函数需要声明为void *(*)(void *).

所以改变这个

 void *matrixCalc(threadCount) 

将成为这个

 void * matrixCalc(void *) 

由于代码似乎试图产生多个线程,所有应该连接perpare空间来存储几个pthread-id.

例如,可以使用如下数组来完成:

pthread_t tid[numberOfThreads] = {0};

然后像这样创建线程:

pthread_create(&tid[i], &attr, matrixCalc, NULL);

将线程号(计数器i)传递给线程也通过定义给它空间

int thread_counts[numberOfThreads] = {0};

分配它并将其作为线程创建的^第 4 ^个参数传递:

 thread_counts[i] = i;
 pthread_create(&tid[i], &attr, matrixCalc, &thread_Counts[i]);

在线程函数中,然后通过修改获取它

void *matrixCalc(threadCount) 
{
  int i, j, sum, tempNum, currentRow;
  currentRow = threadCount;
  ...

像这样:

void * matrixCalc(void * pv) 
{
  int i, j, sum, tempNum, currentRow;
  currentRow = *((int*) pv);
  ...

最后加入所有线程pthread_join(),用循环替换单个调用:

for (i = 0; i < numberOfThreads; ++i)
{
  pthread_join(tid[i], NULL);  
}