Object profiing, can be enabled/disabled with `kill -27 <pid>` (Ruby 2.1.1 version)

profiler.rb

begin                                                                                                                                                                             
  require 'objspace'                                                                                                                                                              
  trap("PROF") do                                                                                                                                                                 
    if $__PROFILING__                                                                                                                                                             
      GC.start                                                                                                                                                                    
      filename = Time.now.strftime("objects-%Y%m%d%H%S.json")                                                                                                                     
      ObjectSpace.dump_all(output: File.open(filename,'w'))                                                                                                                       
      ObjectSpace.trace_object_allocations_stop                                                                                                                                   
      $__PROFILING__ = false                                                                                                                                                      
      puts "STOPPED OBJECT TRACE => #{filename}"                                                                                                                                  
    else                                                                                                                                                                          
      ObjectSpace.trace_object_allocations_start                                                                                                                                  
      $__PROFILING__ = true                                                                                                                                                       
      puts "STARTED OBJECT TRACE"                                                                                                                                                 
    end                                                                                                                                                                           
  end                                                                                                                                                                             
rescue LoadError                                                                                                                                                                  
  puts "Profiling not started, since we're on #{RUBY_VERSION} (< 2.1)"                                                                                                            
end

Here's the Ruby 2.0 version

begin                                                                                                                                                                             
  require 'json'                                                                                                                                                                  
  trap("PROF") do                                                                                                                                                                 
    filename = Time.now.strftime("objects-%Y%m%d%H%S.json")                                                                                                                       
    counts = ObjectSpace.each_object.inject(Hash.new(0)) do |h, o|                                                                                                                
      h.tap { |h| h[o.class] += 1 }                                                                                                                                               
    end                                                                                                                                                                           
    puts counts.inspect                                                                                                                                                           
    File.open(filename, 'w') { |f| f << counts.to_json }                                                                                                                          
  end                                                                                                                                                                             
  puts "'kill -27 #$PID' to profile"                                                                                                                                              
rescue                                                                                                                                                                            
  puts $!.to_s                                                                                                                                                                    
end