C语言中的多线程错误分割错误

我正在尝试使用多线程将两个矩阵相乘。在这里，我在linux中使用gcc编译程序，并通过输入线程数来运行

gcc multiThread.c -o test -lpthread
./test 4

在这里，我对N*N的矩阵执行乘法，其中N从10开始到1000，间隔为10，并计算每次迭代的执行时间。当我运行程序时，它给出了一个分段错误。请帮忙

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

int SIZE = 10;   // Size by SIZE matrices
int num_thrd;   // number of threads

int A[2000][2000], B[2000][2000], C[2000][2000];

// initialize a matrix
void init_matrix(int m[SIZE][SIZE])
{
  int i, j;
  for (i = 0; i < SIZE; i++)
    for (j = 0; j < SIZE; j++)
      m[i][j] = rand() % 100 + 1;
}

// thread function: taking "slice" as its argument
void* multiply(void* slice)
{
  int s = (int)slice;   // retrive the slice info
  int from = (s * SIZE)/num_thrd; // note that this 'slicing' works fine
  int to = ((s+1) * SIZE)/num_thrd; // even if SIZE is not divisible by num_thrd
  int i,j,k;

  printf("computing slice %d (from row %d to %d)\n", s, from, to-1);
  for (i = from; i < to; i++)
  {  
    for (j = 0; j < SIZE; j++)
    {
      C[i][j] = 0;
      for ( k = 0; k < SIZE; k++)
    C[i][j] += A[i][k]*B[k][j];
    }
  }
  printf("finished slice %d\n", s);
}

int main(int argc, char* argv[])
{
  FILE *outFile;
  outFile = fopen("Algorithm3_Times.txt", "r");
  pthread_t* thread;  // pointer to a group of threads
for(int ini=0; ini<100; ini++)
{


  int i;

  if (argc!=2)
  {
    printf("Usage: %s number_of_threads\n",argv[0]);
    exit(-1);
  }

  num_thrd = atoi(argv[1]);
  init_matrix(A);
  init_matrix(B);
  clock_t start = clock();
  thread = (pthread_t*) malloc(num_thrd*sizeof(pthread_t));
  // this for loop not entered if threadd number is specified as 1
  for (i = 1; i < num_thrd; i++)
  {
    // creates each thread working on its own slice of i
    if (pthread_create (&thread[i], NULL, multiply, (void*)i) != 0 )
    {
      perror("Can't create thread");
      free(thread);
      exit(-1);
    }
  }

  // main thread works on slice 0
  // so everybody is busy
  // main thread does everything if threadd number is specified as 1
  multiply(0);

  // main thead waiting for other thread to complete
  for (i = 1; i < num_thrd; i++)
    pthread_join (thread[i], NULL);

  clock_t end = clock();

  float time = (end - start)*1000 / CLOCKS_PER_SEC;
  fprintf(outFile,"time taken for Multiplication using %d", num_thrd);
  fprintf(outFile," threads =  %f", time);
  fprintf(outFile," milliseconds \n");
  if (thread != NULL)
  {
      free(thread);
      thread = NULL;
  }
  SIZE += 10;

 }

  printf("calculation completed.\n\n");
  return 0;

}

#包括
#包括
#包括
#包括
int SIZE=10；//按大小排列的矩阵
int num_thrd；//线程数
INTA[2000][2000],B[2000][2000],C[2000][2000];；
//初始化矩阵
void init_矩阵（int m[SIZE][SIZE]）
{
int i，j；
对于（i=0；ifor（int ini=0；iniC）是一种硬语言，特别是因为默认情况下运行时错误不包含有用的调试信息。这就是调试器的作用

我是如何用docker/alpine调试的：

将代码放入
~/gcc/t.c
以共享给我的docker
docker-run-rm-it-v
ls-d~
/gcc:/code-alpine
apk添加build base gdb musl dbg
以安装gcc&friends、gdb和musl dbg，我需要在标准库中调试segfault
cd/code
gcc-gtc-ot
gdb t
现在是我的调试器会话：

GNU gdb (GDB) 8.0.1

[ ... preamble removed for brevity ... ]

Reading symbols from t...done.
(gdb) run 1
Starting program: /code/t 1
warning: Error disabling address space randomization: Operation not permitted
computing slice 0 (from row 0 to 9)
finished slice 0

Program received signal SIGSEGV, Segmentation fault.
vfprintf (f=0x0, fmt=0x560896553020 "time taken for Multiplication using %d",
    ap=ap@entry=0x7ffcb18b29f8) at src/stdio/vfprintf.c:671
671 src/stdio/vfprintf.c: No such file or directory.
(gdb) bt
#0  vfprintf (f=0x0,
    fmt=0x560896553020 "time taken for Multiplication using %d",
    ap=ap@entry=0x7ffcb18b29f8) at src/stdio/vfprintf.c:671
#1  0x00007fa6ef0c056f in fprintf (f=<optimized out>, fmt=<optimized out>)
    at src/stdio/fprintf.c:9
#2  0x0000560896552ee2 in main (argc=2, argv=0x7ffcb18b2b68) at t.c:87

我们可以看一看这行代码，做一些思考，最终来看看
outFile
的定义：

outFile = fopen("Algorithm3_Times.txt", "r");

啊哈！我们本想写外文，但我们打开了它来阅读！我改为打开来写：

  outFile = fopen("Algorithm3_Times.txt", "w");

并且您的程序运行（注意下面我只显示前10行）

现在您已经了解了
gdb
，您可以开始在特定行中输入gdb
break
语句，并解决任何剩余的bug。我的程序似乎从未完成，但我没有给它太多时间。
如果您想用C做任何远程复杂的事情，您确实需要开始使用调试器。当我终于意识到我浪费了多少生命，我真的踢了我自己，因为我没有学习<代码> GDB < /C> >。不要犯同样的错误。我使用了调试器！为什么你要标记C++？这不是主要问题，而是调用<代码> iITIX矩阵（A）；< /COD>和<代码>；

没有初始化您认为是的数组部分。是否收到编译器关于不兼容指针类型的警告？

  outFile = fopen("Algorithm3_Times.txt", "w");

/code # ./t 10  |head
computing slice 1 (from row 1 to 1)
finished slice 1
computing slice 2 (from row 2 to 2)
computing slice 3 (from row 3 to 3)
finished slice 3
finished slice 2
computing slice 4 (from row 4 to 4)
finished slice 4
computing slice 5 (from row 5 to 5)
finished slice 5