high CPU usage and freezing in Python REPL with half space character (U+200C)

Bug report

Bug description:

When entering comments in Python's REPL that contain a Half Space character (U+200C) the REPL experiences 100% CPU usage and becomes unresponsive (freezes) when using the up arrow to retrieve previous code line

https://unicode-explorer.com/c/200C

Steps to Reproduce:

Go to Python REPL
Paste the following lines (for Windows, use F3 to activate paste mode):

# Half space ‌text
# Up arrow key

Press the up arrow key to navigate back to the previous line (# Half space ‌text)

(If it doesn't work for you, go to the end of the line # Up arrow key and press the up button. It should freeze now. You can use Ctrl+C to interrupt the program, which resolves the freeze.)

in terminal this looks like this:

>>> # Half space \u200ctext
... # Up arrow key

This problem also exists in Windows when using F3 (to active the paste mode):

In Linux no need to active paste mode:

I can't check if this problem exists on previous python version because they break each line so i cant use up arrow to go to the previous line.

Half Space character is often used in Persian and I think in other languages that utilize right-to-left . It helps in adjusting the spacing between characters for better readability

Also a small note: when I use the half space at the end and no text after it, there is no problem:

# Half space ‌
# Up arrow key

in terminal:

>>> # Half space \u200c
... # Up arrow key

System Information:

Linux: Python 3.13.0rc2 | Fedora 40
Windows Python 3.13.0rc3 | Windows 11

CPython versions tested on:

3.13

Operating systems tested on:

Linux, Windows

Linked PRs

My python versoin is 3.11.5. It seems nothing happen in win10.

My python versoin is 3.11.5. It seems nothing happen in win10.

Then you, probably, use old repl. I suppose OP used new repl, enabled in the CPython 3.13 by default, see: https://docs.python.org/3.13/whatsnew/3.13.html#a-better-interactive-interpreter

I hope this message finds you well. I was wondering if anyone is currently addressing this issue. If it’s alright, would it be possible for me to create a PR? I may already find the cause of the mistake.
Thank you!

@imfeh2

@imfeh2, sure. So far nobody confirm that can reproduce issue.

Feel free to open a PR, see also https://devguide.python.org/getting-started/pull-request-lifecycle/#making-good-prs

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high CPU usage and freezing in Python REPL with half space character (U+200C) #124927

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high CPU usage and freezing in Python REPL with half space character (U+200C) #124927

Description

Bug report

Bug description:

Steps to Reproduce:

System Information:

CPython versions tested on:

Operating systems tested on:

Linked PRs

Activity

qqwqqw689 commented on Oct 3, 2024

skirpichev commented on Oct 3, 2024

imfeh2 commented on Oct 5, 2024

skirpichev commented on Oct 5, 2024

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