`KeyboardInterrupt` not handled while evaluating a tight `while` loop condition on Python 3.13
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@markshannon is already working on this.
Since Feb 19, 2025.
3.13
interpreter-core
type-bug
- Dominant language
- Python
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Description
Bug report
Bug description:
Consider the following infinite loop:
# test.py
class A:
def __init__(self):
self.shutdown_requested = False
def start(self):
pass
def stop(self):
self.shutdown_requested = True
def loop_1(a: A):
try:
while not a.shutdown_requested:
pass
except KeyboardInterrupt:
print("in except block")
finally:
print("in finally block")
a.stop()
def loop_2(a: A):
try:
while True:
if a.shutdown_requested:
break
except KeyboardInterrupt:
print("in except block")
finally:
print("in finally block")
a.stop()
if __name__ == "__main__":
a = A()
a.start()
loop_1(a)
# loop_2(a)
^CTraceback (most recent call last):
File "/home/harshil/test.py", line 40, in <module>
loop_1(a)
~~~~~~^^^
File "/home/harshil/test.py", line 14, in loop_1
while not a.shutdown_requested:
^^^^^^^^^^^^^^^^^^^^
KeyboardInterrupt
If you run this program on Python 3.13 (3.13.1, and 3.13.2), pressing Ctrl+C does not execute the except and finally blocks in the case of loop_1(), but it works for loop_2().
If you run the same program on 3.14a5, or below 3.13, the issue does not happen, and the print statements are visible too.
CPython versions tested on:
3.12, 3.13, 3.13t, 3.14, 3.10
Operating systems tested on:
Linux
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