ruby-changes:41867
From: tenderlove <ko1@a...>
Date: Fri, 26 Feb 2016 08:22:54 +0900 (JST)
Subject: [ruby-changes:41867] tenderlove:r53941 (trunk): Reduce system calls by activating the `did_you_mean` gem.
tenderlove 2016-02-26 08:23:30 +0900 (Fri, 26 Feb 2016) New Revision: 53941 https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=53941 Log: Reduce system calls by activating the `did_you_mean` gem. Activating the gem puts the gem on the load path, where simply requiring the file will search every gem that's installed until it can find a gem that contains the `did_you_mean` file. Calling RubyGems' `require` will search each installed gem until it can find one that contains the file it should require. This means that the more gems you have installed, the longer it can take to require that gem. To see this in action, lets compare the number of `stat` calls for a "bare require" vs the number of `stat` calls for a require that follows a gem activation by using these two programs: ``` [aaron@TC rubygems (master)]$ cat req_dym.rb begin require 'did_you_mean' rescue LoadError end [aaron@TC rubygems (master)]$ cat gem_dym.rb begin gem 'did_you_mean' require 'did_you_mean' rescue Gem::LoadError, LoadError end ``` The first program just requires the `did_you_mean` gem, where the second one activates the gem, then requires it. We can count the number of `stat` calls using `dtrace`: ``` [aaron@TC rubygems (master)]$ ruby -v ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin15] [aaron@TC rubygems (master)]$ sudo dtrace -q -n 'syscall::stat*:entry { printf("%s\n", copyinstr(arg0)); }' -c`rbenv which ruby`" --disable-did_you_mean req_dym.rb" | wc -l dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 283 [aaron@TC rubygems (master)]$ sudo dtrace -q -n 'syscall::stat*:entry { printf("%s\n", copyinstr(arg0)); }' -c`rbenv which ruby`" --disable-did_you_mean gem_dym.rb" | wc -l dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 13 ``` The "bare require" version does over 10x the number of stat calls compared to the "gem, then require" version. Of course the number for the first one depends on the number of gems you have installed that sort before the `did_you_mean` gem. Lets also look at trunk Ruby: ``` [aaron@TC rubygems (master)]$ ruby -v ruby 2.4.0dev (2016-02-25 trunk 53940) [x86_64-darwin15] [aaron@TC rubygems (master)]$ sudo dtrace -q -n 'syscall::stat*:entry { printf("%s\n", copyinstr(arg0)); }' -c`rbenv which ruby`" --disable-did_you_mean req_dym.rb" | wc -l dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 2325 [aaron@TC rubygems (master)]$ sudo dtrace -q -n 'syscall::stat*:entry { printf("%s\n", copyinstr(arg0)); }' -c`rbenv which ruby`" --disable-did_you_mean gem_dym.rb" | wc -l dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 dtrace: error on enabled probe ID 3 (ID 826: syscall::stat64:entry): invalid user access in action #1 at DIF offset 24 685 ``` This change will reduce the number of `stat` calls on trunk Ruby too, but since this installation doesn't have the `did_you_mean` gem, RubyGems is still reading every gem spec file so that it can raise a `Gem::LoadError` exception with a nice error message. If we can modify RubyGems a little, it may be possible to drop the number of stat calls even on a Ruby installation that doesn't have the `did_you_mean` gem. Modified files: trunk/ChangeLog trunk/gem_prelude.rb Index: gem_prelude.rb =================================================================== --- gem_prelude.rb (revision 53940) +++ gem_prelude.rb (revision 53941) @@ -1,7 +1,8 @@ https://github.com/ruby/ruby/blob/trunk/gem_prelude.rb#L1 if defined?(Gem) require 'rubygems.rb' begin + gem 'did_you_mean' require 'did_you_mean' - rescue LoadError + rescue Gem::LoadError, LoadError end if defined?(DidYouMean) end Index: ChangeLog =================================================================== --- ChangeLog (revision 53940) +++ ChangeLog (revision 53941) @@ -1,3 +1,11 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1 +Fri Feb 26 08:11:58 2016 Aaron Patterson <tenderlove@r...> + + * gem_prelude.rb: Reduce system calls by activating the `did_you_mean` + gem before requiring the gem. Activating the gem puts the gem on + the load path, where simply requiring the file will search every gem + that's installed until it can find a gem that contains the + `did_you_mean` file. + Thu Feb 25 19:04:13 2016 Martin Duerst <duerst@i...> * enc/unicode/case-folding.rb: Adding possibility for debugging output -- ML: ruby-changes@q... Info: http://www.atdot.net/~ko1/quickml/