From 76618061b92e23a53b78b7ec3a173cb0e7749b4a Mon Sep 17 00:00:00 2001 From: =?utf8?q?=C5=81ukasz=20Langa?= Date: Mon, 16 Apr 2018 17:33:59 -0700 Subject: [PATCH] [lib2to3] Make grammar pickling faster (#6491) * Now uses pickle protocol 4 * Doesn't wrap the grammar's `__dict__` in ordered dictionaries anymore as dictionaries in Python 3.6+ are ordered by default This still produces deterministic pickles (that hash the same with MD5). Tested with different PYTHONHASHSEED values. --- Lib/lib2to3/pgen2/grammar.py | 27 ++----------------- .../2018-04-16-16-21-09.bpo-23403.rxR1Q_.rst | 1 + 2 files changed, 3 insertions(+), 25 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2018-04-16-16-21-09.bpo-23403.rxR1Q_.rst diff --git a/Lib/lib2to3/pgen2/grammar.py b/Lib/lib2to3/pgen2/grammar.py index 088c58bfa9..c00cb2248d 100644 --- a/Lib/lib2to3/pgen2/grammar.py +++ b/Lib/lib2to3/pgen2/grammar.py @@ -86,21 +86,9 @@ class Grammar(object): self.start = 256 def dump(self, filename): - """Dump the grammar tables to a pickle file. - - dump() recursively changes all dict to OrderedDict, so the pickled file - is not exactly the same as what was passed in to dump(). load() uses the - pickled file to create the tables, but only changes OrderedDict to dict - at the top level; it does not recursively change OrderedDict to dict. - So, the loaded tables are different from the original tables that were - passed to load() in that some of the OrderedDict (from the pickled file) - are not changed back to dict. For parsing, this has no effect on - performance because OrderedDict uses dict's __getitem__ with nothing in - between. - """ + """Dump the grammar tables to a pickle file.""" with open(filename, "wb") as f: - d = _make_deterministic(self.__dict__) - pickle.dump(d, f, 2) + pickle.dump(self.__dict__, f, pickle.HIGHEST_PROTOCOL) def load(self, filename): """Load the grammar tables from a pickle file.""" @@ -141,17 +129,6 @@ class Grammar(object): print("start", self.start) -def _make_deterministic(top): - if isinstance(top, dict): - return collections.OrderedDict( - sorted(((k, _make_deterministic(v)) for k, v in top.items()))) - if isinstance(top, list): - return [_make_deterministic(e) for e in top] - if isinstance(top, tuple): - return tuple(_make_deterministic(e) for e in top) - return top - - # Map from operator to number (since tokenize doesn't do this) opmap_raw = """ diff --git a/Misc/NEWS.d/next/Library/2018-04-16-16-21-09.bpo-23403.rxR1Q_.rst b/Misc/NEWS.d/next/Library/2018-04-16-16-21-09.bpo-23403.rxR1Q_.rst new file mode 100644 index 0000000000..8116e3b9ce --- /dev/null +++ b/Misc/NEWS.d/next/Library/2018-04-16-16-21-09.bpo-23403.rxR1Q_.rst @@ -0,0 +1 @@ +lib2to3 now uses pickle protocol 4 for pre-computed grammars. -- 2.40.0