[ruby-core:31798] [Bug #3726] require degradation from 1.9.1

Bug #3726: require degradation from 1.9.1
http://redmine.ruby-lang.org/issues/show/3726

Author: Yura Sokolov
Status: Open, Priority: Normal
Target version: 1.9.2
ruby -v: ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]

I have two simultaneous installation of ruby 1.9.1 and ruby 1.9.2.
There are installed gems ( pg in particular ).

Having file 5.rb containing

  require 'pg'

i have following results:

For ruby 1.9.1:

# time /opt/ruby1.9.1/bin/ruby1.9 5.rb

real	0m0.086s
user	0m0.056s
sys	0m0.008s

# time /opt/ruby1.9.1/bin/ruby1.9 -r profile 5.rb
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
100.00     0.03      0.03        2    15.00    25.00  Kernel.require
  0.00     0.03      0.00      131     0.00     0.00  Module#method_added
  0.00     0.03      0.00        3     0.00     0.00  Class#inherited
  0.00     0.03      0.00        1     0.00     0.00  String#=~
  0.00     0.03      0.00       13     0.00     0.00  BasicObject#singleton_method_added
  0.00     0.03      0.00        4     0.00     0.00  IO#set_encoding
  0.00     0.03      0.00        1     0.00    30.00  #toplevel

real	0m0.116s
user	0m0.076s
sys	0m0.020s


For ruby 1.9.2:

# time /opt/ruby1.9.2/bin/ruby1.9 5.rb

real	0m0.449s
user	0m0.296s
sys	0m0.048s

# time /opt/ruby1.9.2/bin/ruby1.9 -r profile 5.rb
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 27.74     0.43      0.43       28    15.36    60.36  Kernel.gem_original_require
  5.16     0.51      0.08     3963     0.02     0.02  Hash#default
  5.16     0.59      0.08       45     1.78     7.33  Array#each
  4.52     0.66      0.07      287     0.24     0.42  String#gsub
  3.23     0.71      0.05      897     0.06     0.06  Module#===
  3.23     0.76      0.05       11     4.55    45.45  Gem::SourceIndex#load_specification
  3.23     0.81      0.05      371     0.13     0.24  Kernel.dup
  3.23     0.86      0.05      265     0.19     0.68  RbConfig.expand
  2.58     0.90      0.04      126     0.32    10.63  Class#new
  2.58     0.94      0.04      374     0.11     0.11  Kernel.initialize_dup
  2.58     0.98      0.04      605     0.07     0.07  Kernel.===
  1.94     1.01      0.03      585     0.05     0.05  Hash#[]=
  1.94     1.04      0.03       31     0.97     4.19  Gem::Requirement#initialize
  1.94     1.07      0.03       11     2.73     2.73  IO#read
  1.94     1.10      0.03       31     0.97     3.23  Array#map!
  1.29     1.12      0.02      531     0.04     0.04  Module#method_added
  1.29     1.14      0.02       27     0.74    85.93  Kernel.require
  1.29     1.16      0.02      363     0.06     0.06  Kernel.instance_variable_set
  1.29     1.18      0.02       59     0.34     0.34  String#scan
  1.29     1.20      0.02       64     0.31     0.63  Array#map
  1.29     1.22      0.02       21     0.95     1.43  Gem::Specification#attribute
  1.29     1.24      0.02       59     0.34     1.53  Gem::Version#initialize
  1.29     1.26      0.02       29     0.69     1.03  Array#select
  0.65     1.27      0.01      308     0.03     0.03  String#==
  0.65     1.28      0.01      159     0.06     0.06  String#to_i
  0.65     1.29      0.01        3     3.33   186.67  Mutex#synchronize
  0.65     1.30      0.01       26     0.38     0.38  Dir#[]
  0.65     1.31      0.01       59     0.17     0.34  Gem::Version#correct?
  0.65     1.32      0.01        1    10.00    10.00  Gem.ruby_engine
  0.65     1.33      0.01       71     0.14     0.14  String#=~
  0.65     1.34      0.01        2     5.00     5.00  Dir#glob
  0.65     1.35      0.01       40     0.25     0.25  Module#attr_accessor
  0.65     1.36      0.01      176     0.06     0.06  Regexp#=~
  0.65     1.37      0.01        9     1.11     1.11  Module#include
  0.65     1.38      0.01        8     1.25     1.25  Time#local
  0.65     1.39      0.01      100     0.10     0.10  Symbol#to_s
  0.65     1.40      0.01        8     1.25     1.25  Comparable.>=
  0.65     1.41      0.01       11     0.91    40.91  Kernel.eval
  0.65     1.42      0.01       47     0.21     0.21  Kernel.object_id
  0.65     1.43      0.01       18     0.56     1.67  Gem::GemPathSearcher#matching_files
  0.65     1.44      0.01        1    10.00    10.00  Gem::SourceIndex#search
  0.65     1.45      0.01      143     0.07     0.07  Hash#[]
  0.65     1.46      0.01      163     0.06     0.06  BasicObject#singleton_method_added
  0.00     1.46      0.00        3     0.00     0.00  Gem::Specification#original_name
  0.00     1.46      0.00        1     0.00   150.00  Hash#each_value
  0.00     1.46      0.00        1     0.00     0.00  Hash#merge!
  0.00     1.46      0.00        1     0.00     0.00  Mutex#initialize
   .......................................................
  0.00     1.46      0.00        1     0.00     0.00  Gem.load_path_insert_index
  0.00     1.46      0.00        1     0.00     0.00  Array#insert
  0.00     1.46      0.00        1     0.00    10.00  Gem.activate
  0.00     1.55      0.00        1     0.00  1550.00  #toplevel

real	0m2.215s
user	0m1.656s
sys	0m0.096s


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