`test_zipfile64.[...].test_strip_removed_large_file_with_dd_no_sig` fails on BigMem runs

[StanFromIreland]

Bug report

Bug description:

For example, in this run:

======================================================================
FAIL: test_strip_removed_large_file_with_dd_no_sig (test.test_zipfile64.TestRepack.test_strip_removed_large_file_with_dd_no_sig)
Should scan for the data descriptor (without signature) of a removed
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.diegorusso-aarch64-bigmem.bigmem/build/Lib/test/test_zipfile64.py", line 214, in test_strip_removed_large_file_with_dd_no_sig
    self.assertLess(peak, self.allowed_memory)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 603662 not less than 204800
----------------------------------------------------------------------

I'm also able to reproduce this locally:

$ ./python -m test test_zipfile64 -u extralargefile -v -m test_strip_removed_large_file_with_dd_no_sig
== CPython 3.16.0a0 (heads/main:f7e5cddcbbb, Jun 24 2026, 20:02:47) [GCC 15.2.1 20260123 (Red Hat 15.2.1-7)]
== Linux-7.0.12-101.fc43.x86_64-x86_64-with-glibc2.42 little-endian
== Python build: debug
== cwd: /home/stan/dev/cpython/build/test_python_worker_124469æ
== CPU count: 16
== encodings: locale=UTF-8 FS=utf-8
== resources (1): extralargefile

Using random seed: 2703420052
0:00:00 load avg: 1.79 mem: 27.0 MiB Run 1 test sequentially in a single process
0:00:00 load avg: 1.79 mem: 27.0 MiB [1/1] test_zipfile64
test_strip_removed_large_file_with_dd_no_sig (test.test_zipfile64.TestRepack.test_strip_removed_large_file_with_dd_no_sig)
Should scan for the data descriptor (without signature) of a removed ... FAIL

======================================================================
FAIL: test_strip_removed_large_file_with_dd_no_sig (test.test_zipfile64.TestRepack.test_strip_removed_large_file_with_dd_no_sig)
Should scan for the data descriptor (without signature) of a removed
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/stan/dev/cpython/Lib/test/test_zipfile64.py", line 215, in test_strip_removed_large_file_with_dd_no_sig
    self.assertLess(peak, self.allowed_memory)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 1027764 not less than 204800

----------------------------------------------------------------------
Ran 1 test in 200.611s

FAILED (failures=1)
test test_zipfile64 failed
0:03:20 load avg: 1.57 mem: 32.0 MiB [1/1/1] test_zipfile64 failed (1 failure) in 3 min 20 sec

== Tests result: FAILURE ==

1 test failed:
    test_zipfile64

Total duration: 3 min 20 sec
Total tests: run=1 (filtered) failures=1
Total test files: run=1/1 (filtered) failed=1
Result: FAILURE

This test was added recently in aec0aed by @danny0838 and @gpshead.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-152190: Fix memory checking failure in test_strip_removed_large_file_with_dd_no_sig #152203

[danny0838]

This is probably a side effect of the patch b6937c5, which increased the chunk size from 8 KiB to io.DEFAULT_BUFFER_SIZE (128 KiB on PC) for no-DD scan, while the allowed memory in test_strip_removed_large_file_with_dd_no_sig remains 200 KiB.

If we agree with the direction of keeping io.DEFAULT_BUFFER_SIZE chunk size, removing the overriding allowed_memory should fix the test error:

cpython/Lib/test/test_zipfile64.py

Line 204 in b6937c5

self.allowed_memory = 200*1024

[gpshead]

Agreed.

…

On Thu, Jun 25, 2026, 6:17 AM Danny Lin ***@***.***> wrote: *danny0838* left a comment (python/cpython#152190) <#152190 (comment)> This is probably a side effect of the patch b6937c5 <b6937c5>, which increased the chunk size from 8 KiB to 1 MiB for no-DD scan, while the allowed memory in test_strip_removed_large_file_with_dd_no_sig remains 200 KiB. If we agree with the direction of keeping 1 MiB chunk size, removing the overriding allowed_memory should fix the test error: https://github.com/python/cpython/blob/b6937c5cf047ce98fe1233fefca2fb23f85bdd51/Lib/test/test_zipfile64.py#L204 — Reply to this email directly, view it on GitHub <#152190?email_source=notifications&email_token=AAAQXC2SVAE2DAX52WOZ7HL5BUQ5TA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINZZHE3DOOBZHA4KM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-4799678988>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAQXCZAF5HSJXS5EB3MLB35BUQ5TAVCNFSNUABEKJSXA33TNF2G64TZHM4DCNJZHA4TMMJ3JFZXG5LFHM2DONBTG42TCOBQGGQXMAQ> . You are receiving this because you were mentioned.Message ID: ***@***.***>