Issue #3924 has been updated by Luis Lavena.


Jon Forums wrote:
> @Luis, if you have time, would you add results to your gist using a patched ruby_1_9_2 build?
> 

Patch doesn't apply against 1.9.2:

C:\Users\Luis\Projects\oss\ruby>git apply require-performance-fix-r31758.patch
require-performance-fix-r31758.patch:115: trailing whitespace.
/*
require-performance-fix-r31758.patch:128: trailing whitespace.
/*
require-performance-fix-r31758.patch:648: trailing whitespace.
                                basename  = rb_funcall(rb_cFile, rb_intern("basename"), 2,
require-performance-fix-r31758.patch:652: trailing whitespace.
                                file_name_with_extension = rb_funcall(rb_cFile, rb_intern("join"), 2,
require-performance-fix-r31758.patch:728: trailing whitespace.
                 * This is the most common case, so optimize for it. If not found, fall
warning: enc/make_encmake.rb has type 100644, expected 100755
error: patch failed: enc/make_encmake.rb:3
error: enc/make_encmake.rb: patch does not apply
warning: ext/extmk.rb has type 100644, expected 100755
error: patch failed: load.c:68
error: load.c: patch does not apply
error: patch failed: test/ruby/test_require.rb:339
error: test/ruby/test_require.rb: patch does not apply
error: patch failed: variable.c:19
error: variable.c: patch does not apply
error: patch failed: vm_core.h:324
error: vm_core.h: patch does not apply


----------------------------------------
Bug #3924: Performance bug (in require?)
http://redmine.ruby-lang.org/issues/3924

Author: Carsten Bormann
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 1.9.3
ruby -v: -


=begin
 Running irb < /dev/null in 1.9.2 causes 3016 calls to lstat64.
 
 For instance, there is a sequence of 28 repetitions each of lstat calls to all 6 non-empty path prefixes of /opt/local/lib/ruby1.9/1.9.1/irb.rb -- a total of 170 lstats apparently just to load this file; another set of lstats then occurs later for another 18 (times 6) times.  Clearly, something is running amok in the calling sequence rb_require_safe -> realpath_rec -> lstat.
 
 Another example: Running a simple test with the baretest gem causes 17008 calls to lstat.  According to perftools.rb, 80 % of the 1.2 seconds of CPU is used in Kernel#gem_original_require (and another 12 in GC, some of which may be caused by this).
=end



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