(GDB) GDB调试技巧，调试命令

调试时查看依赖DSO

pidof tvm_rpc_server
cat /proc/<pid_of_tvm_rpc_server>/maps

子进程调试

1.vscode -- launch.json

"setupCommands": [
  {
    "description": "为 gdb 启用整齐打印",
    "text": "-enable-pretty-printing",
    "ignoreFailures": true
  }, {
    "description": "libs for gdb",
    "text": "set environment LD_LIBRARY_PATH=${workspaceFolder}/output/cpu_simu_dev/bin:$LD_LIBRARY_PATH",
    "ignoreFailures": false
  }, {
    "description": "debug forked child",
    "text": "-gdb-set follow-fork-mode child",
    "ignoreFailures": false
  }

调试跟try{...} catch(...){...}相关的问题（表现为崩溃后，调用栈没有用户代码，或者没有GDB中断）。

点击暂停调试，调试控制台中执行：

-exec catch throw

2.gdb

gdb --args ./tvm_rpc_server --port=9080
gdb> set follow-fork-mode child
gdb> catch throw

补充知识：catch point

有时程序中有未捕获的异常会导致程序异常的行为甚至导致程序的直接退出。 这对服务器程序来说是不可接受的。

可以使用gdb的catch命令来帮助我们调试异常。

使用gdb捕获异常的扔出点（相当于在扔出异常的地方添加断点）：

catch throw

使用gdb捕获线程退出（相当于在线程退出的时候添加断点）：

catch pthread_exit

这样，如果相应的事件发生，gdb就会中断程序的执行， 就可以使用gdb的bt命令来检查出现错误的调用栈了。

cache命令：

(gdb) help catch
Set catchpoints to catch events.
Raised signals may be caught:
  catch signal              - all signals
  catch signal <signame>    - a particular signal
Raised exceptions may be caught:
  catch throw               - all exceptions, when thrown
  catch throw <exceptname>  - a particular exception, when thrown
  catch catch               - all exceptions, when caught
  catch catch <exceptname>  - a particular exception, when caught
Thread or process events may be caught:
  catch thread_start        - any threads, just after creation
  catch thread_exit         - any threads, just before expiration
  catch thread_join         - any threads, just after joins
Process events may be caught:
  catch start               - any processes, just after creation
  catch exit                - any processes, just before expiration
  catch fork                - calls to fork()
  catch vfork               - calls to vfork()
  catch exec                - calls to exec()
Dynamically-linked library events may be caught:
  catch load                - loads of any library
  catch load <libname>      - loads of a particular library
  catch unload              - unloads of any library
  catch unload <libname>    - unloads of a particular library
The act of your program's execution stopping may also be caught:
  catch stop

C++ exceptions may be caught:
  catch throw               - all exceptions, when thrown
  catch catch               - all exceptions, when caught

Do "help set follow-fork-mode" for info on debugging your program
after a fork or vfork is caught.

Do "help breakpoints" for info on other commands dealing with breakpoints.

参考：

使用gdb调试异常

gdb doc -- Setting Catchpoints

• vscode调试补充1

出现找不到glibc的情况。

无法打开“pthread_join_common.c”: 无法读取文件'vscode-remote://ssh-remote+192.168.33.205/build/glibc-S9d2JN/glibc-2.27/nptl/pthread_join_common.c' (Error: 无法解析不存在的文件 'vscode-remote://ssh-remote+192.168.33.205/build/glibc-S9d2JN/glibc-2.27/nptl/pthread_join_common.c')。

此时在launch.json中添加如下设置：

"sourceFileMap": {
   "/build/glibc-S9d2JN": "/usr/src/glibc"
}

• gdb调试补充
  
  调试时，查看进程空间调用的DSO及其路径，内存map：

cat /proc/<pid>/maps