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New REPL crash (and terminal display issues) after a breakpoint and by sending Ctrl + D input #129614
Description
Bug report
Bug description:
In a really specific scenario, the terminal can go crazy and becomes unresponsive:
bug.mp4
Steps to reproduce:
- Create an
issue.pyfile, with a breakpoint set (echo 'breakpoint()' > issue.py). - Run
issue.pyin interactive mode:python -i issue.py - Press C to continue when hitting the breakpoint.
- Start typing something, e.g.
help( - Input Ctrl + D, as if you wanted to exit the terminal. Nothing happens (as it should).
- Input Ctrl + C, as if you wanted to clear the line.
If no breakpoint was hit before, this works as expected:
>>> help( # hit Ctrl + D then Ctrl + C
KeyboardInterruptNote trying to reproduce on Python 3.12, the following happens:
--Return--
> /home/victorien/ws/pydantic/issue.py(1)<module>()->None
-> breakpoint()
(Pdb) c
>>> help( # hit Ctrl + D then Ctrl + C
Program interrupted. (Use 'cont' to resume).
--Return--
> /home/victorien/.local/share/uv/python/cpython-3.12.7-linux-x86_64-gnu/lib/python3.12/pdb.py(271)sigint_handler()->None
-> self.set_trace(frame)
Traceback (most recent call last):
File "/home/victorien/.local/share/uv/python/cpython-3.12.7-linux-x86_64-gnu/lib/python3.12/pdb.py", line 271, in sigint_handler
self.set_trace(frame)
File "/home/victorien/.local/share/uv/python/cpython-3.12.7-linux-x86_64-gnu/lib/python3.12/bdb.py", line 94, in trace_dispatch
return self.dispatch_return(frame, arg)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/victorien/.local/share/uv/python/cpython-3.12.7-linux-x86_64-gnu/lib/python3.12/bdb.py", line 153, in dispatch_return
self.user_return(frame, arg)
File "/home/victorien/.local/share/uv/python/cpython-3.12.7-linux-x86_64-gnu/lib/python3.12/pdb.py", line 362, in user_return
self.interaction(frame, None)
File "/home/victorien/.local/share/uv/python/cpython-3.12.7-linux-x86_64-gnu/lib/python3.12/pdb.py", line 428, in interaction
self._cmdloop()
File "/home/victorien/.local/share/uv/python/cpython-3.12.7-linux-x86_64-gnu/lib/python3.12/pdb.py", line 390, in _cmdloop
self.cmdloop()
File "/home/victorien/.local/share/uv/python/cpython-3.12.7-linux-x86_64-gnu/lib/python3.12/cmd.py", line 126, in cmdloop
line = input(self.prompt)
^^^^^^^^^^^^^^^^^^
RuntimeError: can't re-enter readline
>>> CPython versions tested on:
3.13
Operating systems tested on:
Linux
Activity
ZeroIntensity commentedon Feb 4, 2025
cc @gaogaotiantian
gaogaotiantian commentedon Feb 4, 2025
Is Ctrl+C a reasonable way to clear the line?
pdbsets up a signal handler forSIGINT(aka Ctrl+C) so users can stop the program with Ctrl+C. I think it conflicts with whatever REPL does. You probably can reproduce this with any code that sets upsignal.signal(signal.SIGINT, some_function).So my question would be - is this even a bug? If the user code sets up a handler for
SIGINTwhich conflicts with the current REPL, whose fault it is?If we consider this a bug, is it a bug for REPL or
pdb? Should REPL behave normal whenSIGINTis set (to anything arbitrary), orpdbshould not do something that REPL dislikes, even though the user can do the exact same thing?I mean we can alleviate this by asking
pdbto reset the sigint handler ininlinemode - but that's actually a behavioral change. It is kind of reasonable, but not backward compatible.I'm not an expert on REPL and we need the expertise in that area.