使用GDB使用OpenMP [英] Using GDB with OpenMP

问题描述

使用GDB我似乎无法为OpenMP线程内打印共享变量的值。例如，使用下面的程序：

Using GDB I can't seem to print the value of shared variables within OpenMP threads. For example, using the following program:

#include <omp.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
  int priv, tid, pub = 100;
  #pragma omp parallel private(priv, tid) num_threads(2)
  {
    tid = omp_get_thread_num();
    priv = tid * 10; 
    #pragma omp sections
    {
      #pragma omp section
      {
        printf("SECTION 0: tid=%d, priv=%d, pub=%d\n", tid, priv, pub);
      }
      #pragma omp section
      {
        printf("SECTION 1: tid=%d, priv=%d, pub=%d\n", tid, priv, pub);
      }

    }
  }
  return EXIT_SUCCESS;
}

在GDB，如果我在第15行（第0的printf的）打破了，我尝试打印的酒馆的价值，我得到的«在目前情况下无符号酒馆。»消息：

In GDB, if I break at line 15 (the printf of section 0), and I try to print the value of "pub", I get the «No symbol "pub" in current context.» message:

Breakpoint 1, main._omp_fn.0 () at omp_simplesec.c:15
15          printf("SECTION 0: tid=%d, priv=%d, pub=%d\n", tid, priv, pub);
(gdb) print pub
No symbol "pub" in current context.

我用gcc编译，并尝试不同的调试标志（-g3 -ggdb3 -gstabs3 -gstabs + 3），没有成功。我也尝试禁用所有优化用-O0，再没有成功。不过，我可以通过使用-gstabs +标志见私有变量的值。

I am compiling with GCC, and tried different debugging flags (-g3 -ggdb3 -gstabs3 -gstabs+3), without success. I also tried disabling all optimizations with -O0, again with no success. However, I can see the value of private variables by using the -gstabs+ flag.

先谢谢了。

推荐答案

当我运行code，我得到了类似的结果。如果你看一下回溯，它会告诉你，你是关系到GCC如何实现的OpenMP的OpenMP的环境中。

When I run your code I get similar results. If you look at the backtrace, it tells you that you are inside an OpenMP environment that is related to how GCC implements OpenMP.

(gdb) backtrace 
#0  main._omp_fn.0 () at tmp.c:15
#1  0x000000000040082e in main (argc=1, argv=0x7fffffffe6c8) at tmp.c:7

您可以得到酒吧的值：

(gdb) up
(gdb) print pub
$1 = 100

但这只让你的酒吧的并行区域前的值。你应该赫里斯托·伊利耶夫检查答案的情况更加详细和更好的描述。

but this only gets you the value of pub before the parallel region. You should check the answer by Hristo Iliev for a much more detailed and better description of the situation.

这篇关于使用GDB使用OpenMP的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！