From ddfcbf85cb34f99b629f2ad621eb7f8c09d38db9 Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Wed, 20 Jan 2016 01:03:18 +0000 Subject: [PATCH] psych: pre-freeze string keys for hashes With the following example, this reduces allocations from 346 to 324 strings when calling Psych.load on a 26-entry hash: -------------------------------8<-------------------------------- require 'psych' require 'objspace' before = {} after = {} str = [ '---', *(('a'..'z').map { |k| "#{k * 11}: 1" }), '' ].join("\n") GC.disable ObjectSpace.count_objects(before) h = Psych.load(str) ObjectSpace.count_objects(after) p(after[:T_STRING] - before[:T_STRING]) -------------------------------8<-------------------------------- Allocating 324 strings for 26 hash keys is still expensive. More work will be needed to reduce allocations further... Tested on x86-64. --- ext/psych/lib/psych/visitors/to_ruby.rb | 1 + 1 file changed, 1 insertion(+) diff --git a/ext/psych/lib/psych/visitors/to_ruby.rb b/ext/psych/lib/psych/visitors/to_ruby.rb index c061da2..2f9408c 100644 --- a/ext/psych/lib/psych/visitors/to_ruby.rb +++ b/ext/psych/lib/psych/visitors/to_ruby.rb @@ -336,6 +336,7 @@ def revive_hash hash, o o.children.each_slice(2) { |k,v| key = accept(k) val = accept(v) + key.freeze if key.instance_of?(String) if key == SHOVEL && k.tag != "tag:yaml.org,2002:str" case v -- EW