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gh-151989: Add with timeout feature + re c module cooperative example#151990

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zang-langyan wants to merge 1 commit into
python:mainfrom
zang-langyan:timeout
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gh-151989: Add with timeout feature + re c module cooperative example#151990
zang-langyan wants to merge 1 commit into
python:mainfrom
zang-langyan:timeout

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@zang-langyan

@zang-langyan zang-langyan commented Jun 23, 2026 •
edited by bedevere-app Bot
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Usage Example:

>>> with timeout(0.2):
...     while True:
...         pass
...
Traceback (most recent call last):
  File "<python-input-1>", line 3, in <module>
    pass
TimeoutError: Timeout

>>> with timeout(0.2):
...     re.match(r"(a+)+b", "a" * 30 + "c")
...
Traceback (most recent call last):
  File "<python-input-2>", line 2, in <module>
    re.match(r"(a+)+b", "a" * 30 + "c")
    ~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../cpython/Lib/re/__init__.py", line 166, in prefixmatch
    return _compile(pattern, flags).prefixmatch(string)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
TimeoutError: Timeout

Performance Summary
Tested on my Macbook Pro M4

  1. No extra overhead outside a timeout block (i.e. timeout_block == NULL timeout check is completely bypassed).
  2. Py_CheckTimeOut
  • fast path (with skip interval ≥ 8) takes 1.1~1.3ns per call;
  • slow path (with skip interval < 8) takes 2.0~6.3ns per call;
  • full calling (without skip interval) takes 10.2ns +- 1.2ns per call.
  1. re module integration
    By tapping into the existing signal‑check counter inside _sre, timeout checks add no measurable overhead to normal regexps while allowing catastrophic backtracking to be safely interrupted within the specified deadline.

@bedevere-app bedevere-app Bot mentioned this pull request Jun 23, 2026
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@StanFromIreland

StanFromIreland commented Jun 23, 2026

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Closing as per issue.

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