gh-117755: Skip test_io.test_constructor() on s390x

[vstinner]

The test allocates 9 223 372 036 854 775 807 bytes (0x7fffffffffffffff) and mimalloc fails with a division by zero on s390x.

• Issue: Python 3.13.0a6 freethreading on s390x: test.test_io.CBufferedReaderTest.test_constructor crash with Floating point exception #117755

[vstinner]

This is a bug in mimalloc. We already worked around a similar (but different) bug in test_decimal by skipping the test: see issue gh-114331. I will try investigate the mimalloc issue later, but I prefer to skip the test for now to unblock my colleague @befeleme with Python 3.13 alpha6.

[hroncok]

...to unblock my colleague @befeleme with Python 3.13 alpha6.

For clarification, we (me and @befeleme) are not blocked on this. The freethreding build in Fedora is disabled on s390x and we can keep it that way for now.

[vstinner]

For clarification, we (me and @befeleme) are not blocked on this. The freethreding build in Fedora is disabled on s390x and we can keep it that way for now.

As the s390x maintainer in Python, I would prefer that you test it to discover real bugs like these ones :-)

[vstinner]

This change is a workaround.

I wrote a fix for the root issue in mimalloc: PR gh-117809.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 FreeBSD14 3.x has failed when building commit a9107fe.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/1232/builds/1984) and take a look at the build logs.
4. Check if the failure is related to this commit (a9107fe) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/1232/builds/1984

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "<frozen getpath>", line 352, in <module>
ValueError: embedded null byte
Warning -- Uncaught thread exception: InterpreterError
Exception in thread Thread-57 (task):
RuntimeError: error evaluating path


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.opsec-fbsd14/build/Lib/threading.py", line 1039, in _bootstrap_inner
    self.run()
    ~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.opsec-fbsd14/build/Lib/threading.py", line 990, in run
    self._target(*self._args, **self._kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.opsec-fbsd14/build/Lib/test/test_interpreters/test_stress.py", line 29, in task
    interp = interpreters.create()
             ~~~~~~~~~~~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.opsec-fbsd14/build/Lib/test/support/interpreters/__init__.py", line 76, in create
    id = _interpreters.create(reqrefs=True)
         ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
interpreters.InterpreterError: interpreter creation failed
k


Traceback (most recent call last):
  File "<frozen getpath>", line 462, in <module>
ValueError: embedded null byte
Warning -- Uncaught thread exception: InterpreterError
Exception in thread Thread-100 (task):
RuntimeError: error evaluating path