【发布时间】：2014-12-30 23:49:52
【问题描述】：
我需要调试用 C 编写的 MPI 应用程序。我想使用将 GDB 手动附加到进程的系统，推荐使用 here（第 6 段）。
问题是，当我尝试打印变量“i”的值时，我得到了这个错误：
No symbol "i" in current context.
set var i=5 也有同样的问题。当我尝试运行info local 时，它只是声明“无语言环境”。
- 系统 Ubuntu 14.04
- MPICC cc (Ubuntu 4.8.2-19ubuntu1) 4.8.2
- GDB GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1。
我用命令编译我的代码
mpicc -o hello hello.c
并执行它
mpiexec -n 2 ./hello
我试图寻找这个问题，但解决方案通常是在 GCC 中不使用任何优化 (-O) 选项，但这对我来说没有用，因为我在这里没有使用它们中的任何一个，我正在使用 MPICC 进行编译。我已经尝试将“i”变量声明为volatile，并使用-g 和-O0 启动mpicc，但没有任何帮助。
DBG 消息
GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word".
Attaching to process 3778
Reading symbols from /home/martin/Dokumenty/Programovani/mpi_trenink/hello...done.
Reading symbols from /usr/lib/x86_64-linux-gnu/libmpich.so.10...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libmpich.so.10
Reading symbols from /lib/x86_64-linux-gnu/libc.so.6...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libc-2.19.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libc.so.6
Reading symbols from /usr/lib/x86_64-linux-gnu/libmpl.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/x86_64-linux-gnu/libmpl.so.1
Reading symbols from /lib/x86_64-linux-gnu/librt.so.1...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/librt-2.19.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/librt.so.1
Reading symbols from /usr/lib/libcr.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libcr.so.0
Reading symbols from /lib/x86_64-linux-gnu/libpthread.so.0...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libpthread-2.19.so...done.
done.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Loaded symbols for /lib/x86_64-linux-gnu/libpthread.so.0
Reading symbols from /lib/x86_64-linux-gnu/libgcc_s.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/x86_64-linux-gnu/libgcc_s.so.1
Reading symbols from /lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/ld-2.19.so...done.
done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /lib/x86_64-linux-gnu/libdl.so.2...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libdl-2.19.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libdl.so.2
Reading symbols from /lib/x86_64-linux-gnu/libnss_files.so.2...Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libnss_files-2.19.so...done.
done.
Loaded symbols for /lib/x86_64-linux-gnu/libnss_files.so.2
0x00007f493e53c9a0 in __nanosleep_nocancel ()
at ../sysdeps/unix/syscall-template.S:81
81 ../sysdeps/unix/syscall-template.S: No such file or directory.
我的代码
#include <stdio.h>
#include <mpi.h>
#include <unistd.h> // sleep()
int main(){
MPI_Init(NULL, NULL);
/* DEBUGGING STOP */
int i = 0;
while(i == 0){
sleep(30);
}
int world_size;
MPI_Comm_size( MPI_COMM_WORLD, &world_size );
int process_id; // casto znaceno jako 'world_rank'
MPI_Comm_rank( MPI_COMM_WORLD, &process_id );
char processor_name[ MPI_MAX_PROCESSOR_NAME ];
int name_len;
MPI_Get_processor_name( processor_name, &name_len );
printf("Hello! - sent from process %d running on processor %s.\n\
Number of processors is %d.\n\
Length of proc name is %d.\n\
***********************\n",
process_id, processor_name, world_size, name_len);
MPI_Finalize();
return 0;
}
【问题讨论】：
-
我试过了，还是不行:-(
-
你能看到任何个变量吗？
-
当我运行
info local时，我看不到任何变量。当我运行info variables时，我看到很多以“__libc”等开头的变量。 -
听起来 gcc 正在注册所有内容。如果你可以在 GDB 中使用
disas main，那么就有可能弄清楚 GCC 使用什么寄存器来表示i。然后您可以运行info reg来确定该特定时间的值。我很乐意帮助分析程序集以找出寄存器是什么，但很抱歉我没有更好的答案来解释为什么您迄今为止的尝试都没有结果。 -
您确定要附加到 MPI 进程而不是父
mpiexec？