Deferring garbage collection cuts the time to run the test suite down (…

…#547).

Just over a third of the time it used to take.

    # before
    Finished in 178.55 seconds
    1148 examples, 0 failures

    #after
    Finished in 66.23 seconds
    1148 examples, 0 failures

spec/spec_helper.rb

@@ -349,3 +349,13 @@ def with_config(config_method_name, value, &block)
 end
 
 ::ActiveSupport::Deprecation.silenced = false
+
+
+Rspec.configure do |config|
+  config.before(:all) do
+    DeferredGarbageCollection.start
+  end
+  config.after(:all) do
+    DeferredGarbageCollection.reconsider
+  end
+end

spec/support/deferred_garbage_collection.rb

@@ -0,0 +1,21 @@
+# Taken from http://makandra.com/notes/950-speed-up-rspec-by-deferring-garbage-collection
+class DeferredGarbageCollection
+
+  DEFERRED_GC_THRESHOLD = (ENV['DEFER_GC'] || 10.0).to_f
+
+  @@last_gc_run = Time.now
+
+  def self.start
+    GC.disable if DEFERRED_GC_THRESHOLD > 0
+  end
+
+  def self.reconsider
+    if DEFERRED_GC_THRESHOLD > 0 && Time.now - @@last_gc_run >= DEFERRED_GC_THRESHOLD
+      GC.enable
+      GC.start
+      GC.disable
+      @@last_gc_run = Time.now
+    end
+  end
+
+end