XMLParser.__init__() leaking refs when called twice #148058
Description
Bug report
Bug description:
Similarly to gh-147998, found with @devdanzin's Claude Code toolkit.
The XMLParser constructor does not care about already created objects if called twice:
cpython/Modules/_elementtree.c
Line 3716 in dea4083
cpython/Modules/_elementtree.c
Line 3720 in dea4083
cpython/Modules/_elementtree.c
Line 3726 in dea4083
etc.
I think it exists since 52467b1
Reproduction
2026-04-03T21:46:41.206031691+0000 maurycy@weiss /home/maurycy/cpython (main) % cat 1.py
import gc
import xml.etree.ElementTree as ET
for i in range(20_000):
p = ET.XMLParser()
del p
if i % 1000 == 0:
gc.collect()
2026-04-03T21:46:41.431691265+0000 maurycy@weiss /home/maurycy/cpython (main) % cat 2.py
import gc
import xml.etree.ElementTree as ET
for i in range(20_000):
p = ET.XMLParser()
p.__init__()
del p
if i % 1000 == 0:
gc.collect()
Then:
2026-04-03T21:50:56.840438090+0000 maurycy@weiss /home/maurycy/cpython (main) % ./python.exe -X showrefcount 1.py
[0 refs, 0 blocks]
2026-04-03T21:51:01.610978599+0000 maurycy@weiss /home/maurycy/cpython (main) % ./python.exe -X showrefcount 2.py
[343430 refs, 302265 blocks]
CPython versions tested on:
CPython main branch
Operating systems tested on:
% cat /etc/debian_version
13.4