使用gdb调试Python程序¶
使用gdb调试Python程序，最核心的一个使用场景就是长时间运行的Python脚本没有响应了，程序卡住了但是不知道卡在哪里，又不能ctrl c了重新跑， 即需要对正在运行的Python程序进行调试。调试的需求也很简单，其实主要是需要查看当前的运行状态，也就是运行到哪里了，上下文变量的值。gdb常用于 调试C/C++程序，但是gdb也可以调试Python程序，只需要在gdb中加载Python的调试模块即可。
环境配置
apt install gdb python3 python3-dbg
# 要安装对应版本的python-dbg，如python3.8-dbg
import time
def fib(n):
time.sleep(0.01)
if n == 1 or n == 0:
return 1
for i in range(n):
return fib(n-1) + fib(n-2)
fib(100)
python fib.py &
gdb python3 148
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Reading symbols from python3...
Reading symbols from /usr/lib/debug/.build-id/02/526282ea6c4d6eec743ad74a1eeefd035346a3.debug...
Attaching to program: /usr/bin/python3, process 148
Reading symbols from /lib/x86_64-linux-gnu/libc.so.6...
Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libc-2.31.so...
Reading symbols from /lib/x86_64-linux-gnu/libpthread.so.0...
Reading symbols from /usr/lib/debug/.build-id/4f/c5fc33f4429136a494c640b113d76f610e4abc.debug...
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Reading symbols from /lib/x86_64-linux-gnu/libdl.so.2...
Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libdl-2.31.so...
Reading symbols from /lib/x86_64-linux-gnu/libutil.so.1...
Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libutil-2.31.so...
Reading symbols from /lib/x86_64-linux-gnu/libm.so.6...
Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/libm-2.31.so...
Reading symbols from /lib/x86_64-linux-gnu/libexpat.so.1...
(No debugging symbols found in /lib/x86_64-linux-gnu/libexpat.so.1)
Reading symbols from /lib/x86_64-linux-gnu/libz.so.1...
(No debugging symbols found in /lib/x86_64-linux-gnu/libz.so.1)
Reading symbols from /lib64/ld-linux-x86-64.so.2...
(No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
0x00007fec057c10da in __GI___select (nfds=nfds@entry=0, readfds=readfds@entry=0x0, writefds=writefds@entry=0x0, exceptfds=exceptfds@entry=0x0, timeout=timeout@entry=0x7fff99ce33a0) at ../sysdeps/unix/sysv/linux/select.c:41
41 ../sysdeps/unix/sysv/linux/select.c: No such file or directory.
| 命令 | 说明 |
|---|---|
| py-bt | 输出Python调用栈 |
| py-bt-full | 输出Python调用栈 |
| py-up | 在调用栈向上一级 |
| py-down | 在调用栈向下一级 |
| py-list | 显示代码 |
| py-locals | 输出locals变量 |
| py-print | 输出 |
(gdb) py-list
1 import time
2 def fib(n):
>3 time.sleep(0.01)
4 if n == 1 or n == 0:
5 return 1
6 for i in range(n):
7 return fib(n-1) + fib(n-2)
8
(gdb) n
4970 in ../Python/ceval.c
(gdb) py-locals
n = 4
(gdb) b
Breakpoint 2 at 0x56acbe: file ../Include/object.h, line 459.
(gdb) c
Continuing.
Breakpoint 2, _PyEval_EvalFrameDefault (f=<optimized out>, throwflag=<optimized out>) at ../Include/object.h:459
459 in ../Include/object.h
... # 省略一些c命令
(gdb) py-locals
n = 3
(gdb) py-bt
Traceback (most recent call first):
File "fib.py", line 4, in fib
if n == 1 or n == 0:
File "fib.py", line 7, in fib
return fib(n-1) + fib(n-2)
... 省略一些输出
(gdb)
(gdb) py-up
#6 Frame 0x7fec0531a580, for file fib.py, line 7, in fib (n=4, i=0)
return fib(n-1) + fib(n-2)
(gdb) py-locals
n = 4
i = 0
(gdb) py-up
#18 Frame 0x7fec0531c040, for file fib.py, line 7, in fib (n=7, i=0)
return fib(n-1) + fib(n-2)
(gdb) py-print i
local 'i' = 0
(gdb) py-print n
local 'n' = 7
(gdb) py-down
#12 Frame 0x7fec0531a900, for file fib.py, line 7, in fib (n=6, i=0)
return fib(n-1) + fib(n-2)
(gdb) py-print n
local 'n' = 6