我想使用gdb 7的支持来debuggingPython“低级进程”。
我需要什么才能做到这一点?
例如:
下级Python的configuration脚本需要运行什么标志?
低级的Python过程必须是Python 2.7还是更新的(我看到在Python源代码树中支持gdb的部分是在提交的时候)? 还是Python 2.7只需要gdb进程本身?
需要安装哪些文件可能不被所有发行版打包? 例如,在packages.ubuntu.com我没有得到python-gdb.py,我相信是必要的任何命中。
知道特定分布需要什么是非常方便的。 我对Ubuntu和Centos需要什么特别感兴趣。
Python似乎需要用--with-pydebug
编译(在Ubuntu 12.04上,包python-dbg
包含一个合适的Python可执行文件,本身称为python-dbg
)。 劣势Python不需要是Python 2.7 – 2.6成功加载2.7 gdb扩展(请参阅下面的调试会话)。 至少在Ubuntu 12.04上,定义gdb扩展名的文件被称为libpython.py
,而不是python-gdb.py
(出于某种原因,构建Python会生成包含这两个文件的构建目录 – 它们是相同的)。
但是,我认为现在不可能使用生产核心文件进行调试:它看起来像Python下级进程的gdb扩展试图获取在生产二进制文件中被优化的变量(例如, PyEval_EvalFrameEx
的f变量)。 看来Linux / gdb,Python还没有达到Illumos上的JavaScript所达到的水平,Bryan Cantrill在这里报告的是能够以这种方式调试生产核心转储:
http://www.infoq.com/presentations/Debugging-Production-Systems
这里是Ubuntu 12.04上的调试会话,显示gdb使用Python 2.7的gdb扩展运行Python 2.6的劣质进程来调试segfault。 首先导致段错误的代码:
~/Downloads/Python-2.6.4$ cat ~/bin/dumpcore.py class Foo: def bar(self): from ctypes import string_at string_at(0xDEADBEEF) # this code will cause Python to segfault def main(): f = Foo() f.someattr = 42 f.someotherattr = {'one':1, 'two':2L, 'three':[(), (None,), (None, None)]} f.bar() if __name__ == "__main__": main()
和调试会话:
~/Downloads/Python-2.6.4$ gdb --args ./python ~/bin/dumpcore.py GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2.1) 7.4-2012.04 Copyright (C) 2012 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". For bug reporting instructions, please see: <http://bugs.launchpad.net/gdb-linaro/>... Reading symbols from /home/john/Downloads/Python-2.6.4/python...done. (gdb) run Starting program: /home/john/Downloads/Python-2.6.4/python /home/john/bin/dumpcore.py [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". Program received signal SIGSEGV, Segmentation fault. 0x0000000000468d67 in PyString_FromString (str=0xdeadbeef <Address 0xdeadbeef out of bounds>) at Objects/stringobject.c:116 116 size = strlen(str); (gdb) py-bt Undefined command: "py-bt". Try "help". (gdb) python >import sys >sys.path.insert(0, "/home/john/Downloads/Python-2.7/Tools/gdb") >import libpython >(gdb) py-bt #10 Frame 0x8f0f90, for file /home/john/Downloads/Python-2.6.4/Lib/ctypes/__init__.py, line 496, in string_at (ptr=3735928559, size=-1) return _string_at(ptr, size) #14 Frame 0x8ebf90, for file /home/john/bin/dumpcore.py, line 5, in bar (self=<Foo(someattr=42, someotherattr={'three': [(), (None,), (None, None)], 'two': 2L, 'one': 1}) at remote 0x7ffff6e03240>, string_at=<function at remote 0x7ffff6e1c990>) string_at(0xDEADBEEF) # this code will cause Python to segfault #17 Frame 0x8ebd80, for file /home/john/bin/dumpcore.py, line 12, in main (f=<Foo(someattr=42, someotherattr={'three': [(), (None,), (None, None)], 'two': 2L, 'one': 1}) at remote 0x7ffff6e03240>) f.bar() #20 Frame 0x8eb680, for file /home/john/bin/dumpcore.py, line 16, in <module> () main() (gdb)