New submission from Serhiy Storchaka: Currently set_lookkey() first tests entry->key == NULL, then entry->hash == hash and entry->key != dummy, and only after that entry->key == key. Proposed patch optimizes the order of comparisons. entry->key == key is tested first as for dicts. And no need to test entry->key != dummy after entry->hash == hash if entry->hash of dummy key is set to -1.
Microbenchmark which demonstrates the best case (a lot of lookups of keys existing in the set). $ ./python -m timeit -s "a = list(range(10**6)); s1 = set(a); s2 = set(a)" -- "s1 <= s2" Unpatched: 10 loops, best of 3: 39.4 msec per loop Patched: 10 loops, best of 3: 35.3 msec per loop ---------- components: Interpreter Core files: set_faster_lookup.patch keywords: patch messages: 234367 nosy: pitrou, rhettinger, serhiy.storchaka priority: normal severity: normal stage: patch review status: open title: Slightly faster set lookup type: performance versions: Python 3.5 Added file: http://bugs.python.org/file37789/set_faster_lookup.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue23282> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
