STINNER Victor added the comment: frozenset constructor has different implementations depending on the input type: set (or frozenset), dict or iterator. The constructor preallocates the frozenset for set and dict, but not for generic iterator and so the set may have a suboptimal size.
Attached patch set_length_hint.patch optimizes also the 3rd case using operator.length_hint (PyObject_LengthHint in C). Since it is an optimization, I prefer to only apply it to Python 3.5 to limit the risk of regression. ---------- keywords: +patch nosy: +haypo title: memory used by frozenset created from set differs from that of frozenset created from other iterable -> set and frozenset constructor should use operator.length_hint to guess the size of the iterator versions: +Python 3.5 -Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4 Added file: http://bugs.python.org/file35255/set_length_hint.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue21507> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
