From Jekyll:

   1  module YerGem
   2    def self.version
   3      yml = YAML.load(File.read(File.join(File.dirname(__FILE__), *%w[.. VERSION.yml])))
   4      "#{yml[:major]}.#{yml[:minor]}.#{yml[:patch]}"
   5    end
   6  end

I was getting this error after unpacking hpricot with gem unpack hpricot. I also tried rake gems:unpack hpricot but it did nothing…

   1  config.gem: Unpacked gem hpricot-0.8.1 in vendor/gems has no specification file. Run 'rake gems:refresh_specs' to fix this. 

The rake gems:refresh_specs command doesn’t work, and appears to have been a temporary workaround, so to fix this error I did this:

   1  cd vendor/gems/hpricot-0.8.1
   2  gem specification hpricot > .specification

I had this issue with Rails 2.3.4.

Installing ruby-prof

First install ruby-prof:

   1  git clone git://github.com/jeremy/ruby-prof.git
   2  cd ruby-prof/
   3  rake gem
   4  sudo gem install pkg/ruby-prof-0.6.1.gem

Note that version 0.6.0 doesn’t work, at least not with Rails 2.1.1. With 0.6.0 I got this message:

   1  `gem install ruby-prof` to use the profiler

Setting up a new environment for profiling

Create config/environments/profiling.rb:

   1  config.cache_classes = true
   2  config.action_controller.consider_all_requests_local = false
   3  config.action_controller.perform_caching             = true
   4  config.action_view.cache_template_loading            = true
   5  
   6  #config.log_level = :debug

Add the new environment to database.yml. You might want to reuse the development database.

Creating a profiling script

Next we’ll create a script that simply fetches the homepage, save the following code in profiling/homepage.rb:

   1  get '/'
   2  say "GET / => #{path}"

Run the script

Now run the script 100 times:

   1  RAILS_ENV=profiling ./script/performance/request -n 100 profiling/homepage.rb

Profiling plain Ruby applications

You can also profile a block of code by calling RubyProf from your code:

   1  require 'ruby-prof'
   2  
   3  # Profile the code
   4  RubyProf.start
   5  ...
   6  [code to profile]
   7  ...
   8  results = RubyProf.stop
   9  
  10  File.open "#{RAILS_ROOT}/tmp/profile-graph.html", 'w' do |file|
  11    RubyProf::GraphHtmlPrinter.new(results).print(file)
  12  end
  13  
  14  File.open "#{RAILS_ROOT}/tmp/profile-flat.txt", 'w' do |file|
  15    RubyProf::FlatPrinter.new(results).print(file)
  16  end
  17  
  18  File.open "#{RAILS_ROOT}/tmp/profile-tree.prof", 'w' do |file|
  19    RubyProf::CallTreePrinter.new(results).print(file)
  20  end

Analyzing results

I prefer to use the RubyProf::CallTreePrinter to output data that kcachegrind can read. The HTML and text data is difficult to read so kcachegrind will definitely make your life easier.

On OSX you can install kcachegrind with Fink (or DarwinPorts):

   1  sudo apt-get update ; sudo apt-get install fink
   2  sudo apt-get install kcachegrind

There’s also WinCacheGrind and MacCacheGrind, but I haven’t tried those.

The stemmer4r gem is fubar. Warning draft snippet…

   1  # gem install stemmer4r
   2  Bulk updating Gem source index for: http://gems.rubyforge.org
   3  Building native extensions.  This could take a while...
   4  ERROR:  While executing gem ... (Gem::Installer::ExtensionBuildError)
   5      ERROR: Failed to build gem native extension.
   6  
   7  ruby extconf.rb install stemmer4r
   8  
   9  Gem files will remain installed in /usr/lib/ruby/gems/1.8/gems/stemmer4r-0.6 for inspection.
  10  Results logged to /usr/lib/ruby/gems/1.8/gems/stemmer4r-0.6/ext/stemmer4r/gem_make.out
  11  
  12  
  13  1. Change path of Ruby executable
  14  
  15  cd /usr/lib/ruby/gems/1.8/gems/stemmer4r-0.6/ext/stemmer4r/
  16  vim extconf.rb
  17  
  18  #!/usr/bin/ruby -w
  19  
  20  to
  21  
  22  #ruby -w
  23  
  24  2. Compile libstemmer_c
  25  
  26  cd /usr/lib/ruby/gems/1.8/gems/stemmer4r-0.6/ext/stemmer4r/libstemmer/
  27  make
  28  
  29  3. Compile stemmer4r
  30  
  31  cd /usr/lib/ruby/gems/1.8/gems/stemmer4r-0.6/ext/stemmer4r/
  32  
  33  Change path:
  34  /usr/local/ruby/lib/ruby/1.8/i686-linux/
  35  To:
  36  /usr/lib/ruby/1.8/x86_64-linux/
  37  
  38  Or wherever you have it installed
  39  
  40  ruby extconf.rb
  41  
  42  
  43  4. Build stemmer4r gem
  44  
  45  
  46  gem build stemmer4r.gemspec
  47  
  48  gem install stemmer4r-0.6.gem
  49  
  50  
  51  Problems
  52  
  53  gcc -shared -rdynamic -Wl,-export-dynamic   -L"/usr/lib" -o stemmer4r.so stemmer4r.o libstemmer_c/libstemmer.o  -lruby1.8  -lpthread -ldl -lcrypt -lm   -lc
  54  /usr/bin/ld: libstemmer_c/libstemmer.o(libstemmer.o): relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC
  55  libstemmer_c/libstemmer.o: could not read symbols: Bad value
  56  collect2: ld returned 1 exit status
  57  make: *** [stemmer4r.so] Error 1
  58  
  59  
  60  Add CFLAGS:
  61  
  62  root@aktagon:/usr/lib/ruby/gems/1.8/gems/stemmer4r-0.6/ext/stemmer4r/libstemmer_c# make
  63  include mkinc.mak
  64  CFLAGS   =  -fPIC
  65  libstemmer.o: $(snowball_sources:.c=.o)
  66          $(AR) -cru $@ $^
  67  

I received the following error when installing Mongrel from the gem repository:

   1  marko@x61s:$ sudo gem install mongrel
   2  Updating metadata for 281 gems from http://gems.rubyforge.org
   3  complete
   4  Building native extensions.  This could take a while...
   5  ERROR:  Error installing mongrel:
   6  	ERROR: Failed to build gem native extension.
   7  
   8  /usr/bin/ruby1.8 extconf.rb install mongrel
   9  extconf.rb:1:in `require': no such file to load -- mkmf (LoadError)
  10  	from extconf.rb:1

The fix is to install the ruby development package:

   1  sudo apt-get install ruby1.8-dev