add object stats

Rakefile

@@ -4,4 +4,19 @@ Rake::TestTask.new do |t|
   t.pattern = "test/test_*.rb"
 end
 
+task :objects do
+  GC.start
+  before = ObjectSpace.count_objects
+  $:.unshift File.expand_path("../lib", __FILE__)
+  require "mime/types"
+  GC.start
+  after = ObjectSpace.count_objects
+  for key, delta in before.keys
+                          .grep(/T_/)
+                          .map { |key| [key, after[key] - before[key]] }
+                          .sort_by { |key, delta| -delta }
+    printf "%10s +%6d\n", key, delta
+  end
+end
+
 task :default => :test