Tool for profiling resource usage in each require call.

$ ruby -Iactiveresource/lib tools/profile_requires.rb active_resource
91.84 KB       3220 obj      4.0 ms  active_resource
83.86 KB       3108 obj      3.3 ms   active_support
69.32 KB       2682 obj      2.6 ms    active_support/vendor
33.98 KB        651 obj      0.6 ms     i18n
94.40 KB        315 obj      4.0 ms  44 KB RSS

1 files changed, 75 insertions, 0 deletions

diff --git a/tools/profile_requires.rb b/tools/profile_requires.rb
new file mode 100644
index 0000000000..68d0de3d80
--- /dev/null
+++ b/tools/profile_requires.rb
@@ -0,0 +1,75 @@
+#!/usr/bin/env ruby
+# Example:
+#   ruby -Iactivesupport/lib tools/profile_requires.rb active_support
+#   ruby -Iactionpack/lib tools/profile_requires.rb action_controller
+abort 'Use REE so you can profile memory and object allocation' unless GC.respond_to?(:enable_stats)
+
+GC.enable_stats
+require 'rubygems'
+Gem.source_index
+require 'benchmark'
+
+module TrackHeapGrowth
+  class << self
+    attr_accessor :indent
+    attr_accessor :stats
+  end
+  self.indent = 0
+  self.stats = []
+
+  def track_growth(file)
+    TrackHeapGrowth.indent += 1
+    heap_before, objects_before = GC.allocated_size, ObjectSpace.allocated_objects
+    result = nil
+    elapsed = Benchmark.realtime { result = yield }
+    heap_after, objects_after = GC.allocated_size, ObjectSpace.allocated_objects
+    TrackHeapGrowth.indent -= 1
+    TrackHeapGrowth.stats << [file, TrackHeapGrowth.indent, elapsed, heap_after - heap_before, objects_after - objects_before] if result
+    result
+  end
+
+  def require(file, *args)
+    track_growth(file) { super }
+  end
+
+  def load(file, *args)
+    track_growth(file) { super }
+  end
+end
+
+Object.instance_eval { include TrackHeapGrowth }
+
+GC.start
+before = GC.allocated_size
+before_rss = `ps -o rss= -p #{Process.pid}`.to_i
+before_live_objects = ObjectSpace.live_objects
+
+path = ARGV.shift
+
+if mode = ARGV.shift
+  require 'ruby-prof'
+  RubyProf.measure_mode = RubyProf.const_get(mode.upcase)
+  RubyProf.start
+end
+
+ENV['NO_RELOAD'] ||= '1'
+ENV['RAILS_ENV'] ||= 'development'
+elapsed = Benchmark.realtime { require path }
+results = RubyProf.stop if mode
+
+GC.start
+after_live_objects = ObjectSpace.live_objects
+after_rss = `ps -o rss= -p #{Process.pid}`.to_i
+after = GC.allocated_size
+usage = (after - before) / 1024.0
+
+if mode
+  File.open("profile_startup.#{mode}.tree", 'w') do |out|
+    RubyProf::CallTreePrinter.new(results).print(out)
+  end
+end
+
+TrackHeapGrowth.stats.reverse_each do |file, indent, sec, bytes, objects|
+  puts "%10.2f KB %10d obj %8.1f ms  %s%s" % [bytes / 1024.0, objects, sec * 1000, ' ' * indent, file]
+end
+puts "%10.2f KB %10d obj %8.1f ms  %d KB RSS" % [usage, after_live_objects - before_live_objects, elapsed * 1000, after_rss - before_rss]