[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Anton Afanasyev added the comment: Hi Antoine, my test works for me. It can be either a = [1, 2, 3] or a = iter([1, 2, 3]) , no matter: both objects will be +1 referenced after taking b = islice(a, 1) . My test failed without patch and passed with one. But your test is more straightforward, thanks. Attaching patches with your test. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Changes by Anton Afanasyev fun@gmail.com: Added file: http://bugs.python.org/file35087/issue21321_3.4_8c8315bac6a8_4.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Changes by Anton Afanasyev fun@gmail.com: Added file: http://bugs.python.org/file35086/issue21321_2.7_e3217efa6edd_4.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Antoine Pitrou added the comment: Thanks. Could you also add a test for the islice_reduce additions? Or is it already tested? I suspect there's a reference leak there: after calling PyObject_GetIter, you should always Py_DECREF(empty_list). Also, with the O code, Py_BuildValue will take a new reference to empty_it, so you should use the N code instead. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Anton Afanasyev added the comment: Hi Antoine, oops you are right about leaks: fixed them in new attached patch. As for testing changes in reduce(): they are already covered by self.pickletest(islice(range(100), *args)). Function pickletest() covers case for pickle dumping/loading of exhausted iterator. -- Added file: http://bugs.python.org/file35091/issue21321_3.4_8c8315bac6a8_5.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Antoine Pitrou added the comment: For the record, checks such as: self.assertEqual(wr() is None, False) are better written: self.assertIsNotNone(wr()) No need to upload a new patch, I'm gonna make the change while committing :-) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Roundup Robot added the comment: New changeset b795105db23a by Antoine Pitrou in branch '3.4': Issue #21321: itertools.islice() now releases the reference to the source iterator when the slice is exhausted. http://hg.python.org/cpython/rev/b795105db23a New changeset a627b3e3c9c8 by Antoine Pitrou in branch 'default': Issue #21321: itertools.islice() now releases the reference to the source iterator when the slice is exhausted. http://hg.python.org/cpython/rev/a627b3e3c9c8 -- nosy: +python-dev ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Antoine Pitrou added the comment: Patch committed, thank you! If you want to provide a patch for 2.7, please say so, otherwise I'll close the issue. -- resolution: - fixed stage: - resolved ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Anton Afanasyev added the comment: Antoine, not sure about 2.7. The issue first arose for me at Python 2.7, so I would prefer issue21321_2.7_e3217efa6edd_4.diff patch be applied. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Roundup Robot added the comment: New changeset 8ee76e1b5aa6 by Antoine Pitrou in branch '2.7': Issue #21321: itertools.islice() now releases the reference to the source iterator when the slice is exhausted. http://hg.python.org/cpython/rev/8ee76e1b5aa6 -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Antoine Pitrou added the comment: Ok, then I've committed to 2.7 too. Thank you very much for contributing! -- status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Anton Afanasyev added the comment: Hi Antoine, I have no found a way to check resource usage in test infrastructure and I don't think it could be done carefully. The only method I found to test issue is straightforward: just to check source iterator is not referenced from itertools.islice() after the latter has been exhausted: a = [random.random() for i in range(10)] before = sys.getrefcount(a) b = islice(a, 5) for i in b: pass after = sys.getrefcount(a) self.assertEqual(before, after) Attaching issue21321_2.7_e3217efa6edd_3.diff and issue21321_3.4_8c8315bac6a8_3.diff patches with this test included in Lib/test/test_itertools.py. -- Added file: http://bugs.python.org/file35076/issue21321_2.7_e3217efa6edd_3.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Changes by Anton Afanasyev fun@gmail.com: Added file: http://bugs.python.org/file35077/issue21321_3.4_8c8315bac6a8_3.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Antoine Pitrou added the comment: Anton, the test is wrong: it is taking a reference to the iterable object (the list), not the iterator. To check the reference to the original iterator is released, something like this would work: import itertools, weakref it = (x for x in (1, 2)) wr = weakref.ref(it) it = itertools.islice(it, 1) wr() is None False list(it) [1] wr() is None # returns True with the patch, False without True -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Antoine Pitrou added the comment: (note I haven't looked at the C part of the patch) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Changes by Terry J. Reedy tjre...@udel.edu: -- versions: +Python 3.5 -Python 3.1, Python 3.2, Python 3.3 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Antoine Pitrou added the comment: Haven't reviewed the patch, but you should definitely add a unit test for the bugfix. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Raymond Hettinger added the comment: The ref-counts in the islice_reduce code don't look to be correct at first glance. -- assignee: - rhettinger ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Anton Afanasyev added the comment: Hi Raymond, do you mean allocation exceptions handling should be more accurate? Attaching fixed version for 3.4 branch. -- Added file: http://bugs.python.org/file35003/issue21321_3.4_8c8315bac6a8_2.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Changes by Antoine Pitrou pit...@free.fr: -- nosy: +pitrou ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
New submission from Anton Afanasyev: This issue results in redundant memory consumption for e.g. in this case: from itertools import * def test_islice(): items, lookahead = tee(repeat(1, int(1e9))) lookahead = islice(lookahead, 10) for item in lookahead: pass for item in items: pass if __name__ == __main__: test_islice() This demo is taken from real case where one needs to look ahead input stream before processing it. For my PC this demo stops with 'Segmentation fault' message after exhausting all PC memory, while running it with patched python consumes only 0.1% of memory till the end. When one uses pure pythonic implementation of itertools.islice() (taken from docs), the issue goes away as well, since this implementation doesn't store redundant reference to source iterator. def islice(iterable, *args): s = slice(*args) it = iter(xrange(s.start or 0, s.stop or sys.maxint, s.step or 1)) nexti = next(it) for i, element in enumerate(iterable): if i == nexti: yield element nexti = next(it) Attaching patch for this issue. Have to change '__reduce__()' method since now unpickling of exhausted 'islice()' object cannot return old source iterator. -- components: Extension Modules files: patch_3.4_8c8315bac6a8.diff keywords: patch messages: 216939 nosy: Anton.Afanasyev, rhettinger priority: normal severity: normal status: open title: itertools.islice() doesn't release reference to the source iterator when the slice is exhausted type: resource usage versions: Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4 Added file: http://bugs.python.org/file34990/patch_3.4_8c8315bac6a8.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21321] itertools.islice() doesn't release reference to the source iterator when the slice is exhausted
Anton Afanasyev added the comment: Added patch for 2.7 version (no need to change '__reduce__()' method since it's not implemented). -- Added file: http://bugs.python.org/file34991/issue21321_2.7_e3217efa6edd.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21321 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
