https://github.com/jschwinger233/pdbattach
Attach pdb to a running Python process.
https://github.com/jschwinger233/pdbattach
attach debug gdb pdb python
Last synced: about 1 month ago
JSON representation
Attach pdb to a running Python process.
- Host: GitHub
- URL: https://github.com/jschwinger233/pdbattach
- Owner: jschwinger233
- License: mit
- Created: 2022-01-25T08:19:46.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2022-06-26T07:46:15.000Z (almost 3 years ago)
- Last Synced: 2025-05-07T04:11:29.566Z (about 1 month ago)
- Topics: attach, debug, gdb, pdb, python
- Language: Python
- Homepage:
- Size: 40 KB
- Stars: 22
- Watchers: 4
- Forks: 0
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# pdbattach
Attach pdb to a running Python process.
## Install
```
python3.8 -mpip install git+https://github.com/jschwinger233/pdbattach.git
```
## Usage
### check process stack
```
sudo pdbattach -p $pid -c 'import traceback; f=open("/tmp/bt", "w+"); print("".join(traceback.format_stack()), file=f, flush=True); f.close()'
```
Then you will find the process's stack backtrace at `/tmp/bt` like:
```
File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
exec(code, run_globals)
File "/usr/lib/python3.8/http/server.py", line 1294, in
test(
File "/usr/lib/python3.8/http/server.py", line 1257, in test
httpd.serve_forever()
File "/usr/lib/python3.8/socketserver.py", line 232, in serve_forever
ready = selector.select(poll_interval)
File "/usr/lib/python3.8/selectors.py", line 415, in select
fd_event_list = self._selector.poll(timeout)
File "", line 1, in
```
### interactive debugging using pdb
Suppose we have a `python3.9` process running with command `python3.9 test.py`, where `test.py` is a simple script:
```python
import time
for i in range(1000):
print(i)
time.sleep(10)
```
then we can attach it:
```bash
$ sudo pdbattach -p $(pgrep -f test.py)
--Return--
> (1)()->None
(Pdb) b test.py:3
Breakpoint 1 at /home/gray/Dropbox/mac.local/Documents/src/github.com/jschwinger233/pdbattach/test.py:3
(Pdb) c
> /home/gray/Dropbox/mac.local/Documents/src/github.com/jschwinger233/pdbattach/test.py(3)()->None
-> print(i)
(Pdb) p i
5
(Pdb) l
1 import time
2 for i in range(1000):
3 B-> print(i)
4 time.sleep(10)
[EOF]
(Pdb) q
```
### inject any code snippets
Suppose we have a simple HTTP server causing memory leak, and we want to use [memray](https://github.com/bloomberg/memray) to do a memory profile by attaching.
Firstly let's enable the tracker:
```bash
sudo pdbattach -p $(pidof python3.9) -c 'import memray; global t; t = memray.Tracker("out.bin"); t.__enter__(); print(t)'
```
You can also put the statements in a script file and run by:
```bash
sudo pdbattach -p $(pidof python3.9) -f mem_track.py
```
Suppose the output of the above injection is:
```
Memray WARNING: Correcting symbol for malloc from 0x421420 to 0x7f0400389110
Memray WARNING: Correcting symbol for free from 0x421890 to 0x7f0400389700
```
Then after a while, stop the tracker and inspect the outcomes:
```bash
sudo pdbattach -p $(pidof python3.9) -c 'import ctypes; ctypes.cast(0x7f03ff6598d0, ctypes.py_object).value.__exit__(None, None, None)'
```
## Known Issues
1. pdb doesn't work properly under multi-thread scenarios. See [issue](https://bugs.python.org/issue41571).
2. ptrace(2) relies on `struct user_regs_struct` whose definition varies across platforms, therefore running pdbattach inside a container (e.g. from docker.io/python:3 image) to attach a host process will cause segmentation fault. See [issue](https://github.com/jschwinger233/pdbattach/issues/4).