New submission from Richard Oudkerk: Currently when a module is garbage collected its dict is purged by replacing all values except __builtins__ by None. This helps clear things at shutdown.
But this can cause problems if it occurs *before* shutdown: if we use a function defined in a module which has been garbage collected, then that function must not depend on any globals, because they will have been purged. Usually this problem only occurs with programs which manipulate sys.modules. For example when setuptools and nose run tests they like to reset sys.modules each time. See for example http://bugs.python.org/issue15881 See also http://bugs.python.org/issue16718 The trivial patch attached prevents the purging behaviour for modules gc'ed before shutdown begins. Usually garbage collection will end up clearing the module's dict anyway. I checked the count of refs and blocks reported on exit when running a trivial program and a full regrtest (which will cause quite a bit of sys.modules manipulation). The difference caused by the patch is minimal. Without patch: do nothing: [20234 refs, 6582 blocks] full regrtest: [92713 refs, 32597 blocks] With patch: do nothing: [20234 refs, 6582 blocks] full regrtest: [92821 refs, 32649 blocks] ---------- files: prevent-purge-before-shutdown.patch keywords: patch messages: 191135 nosy: sbt priority: normal severity: normal status: open title: Stop purging modules which are garbage collected before shutdown versions: Python 3.4 Added file: http://bugs.python.org/file30583/prevent-purge-before-shutdown.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue18214> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
