patch to the RBS to make it use native driver for the benchmarks where available, instead of the just "ruby"

gistfile1.txt

diff --git a/rakelib/bench.rake b/rakelib/bench.rake
index faa4a5a..81c1386 100644
--- a/rakelib/bench.rake
+++ b/rakelib/bench.rake
@@ -6,6 +6,7 @@
 # updates are done manually to ensure stability.
 #
 # see utils/README for more information
+require 'rbconfig'

 BASEDIR         = File.expand_path(File.dirname(__FILE__) + "/..")
 MONITOR         = BASEDIR + "/utils/monitor.rb"
@@ -14,17 +15,21 @@ RBS_DIR         = BASEDIR + "/benchmarks"
 RESULTS_DIR     = BASEDIR + "/results"
 RBS_RESULTS_DIR = RESULTS_DIR + "/rbs"
 WEB_DIR         = RESULTS_DIR + "/web"
-
 ITERATIONS      = (ENV['ITERATIONS'] || 5).to_i
 TIMEOUT         = (ENV['TIMEOUT'] || 300).to_i
 METER_MEMORY    = ENV['METER_MEMORY'] || 'yes'
-VM              = ENV['VM'] || "ruby"
+config          = RbConfig::CONFIG
+RUBY_BIN        = File::join(config['bindir'], config['ruby_install_name']) + config['EXEEXT']
+VM              = ENV['VM'] || RUBY_BIN
+puts VM

 def command(name)
-  # note that we use ruby here
-  # so that we'll be using a "stable" ruby for driving the monitor
-  # thus the test candidate ruby will only be running the test.
-  "ruby #{MONITOR} #{TIMEOUT} '#{VM}' #{RUNNER} #{name} #{ITERATIONS} #{report} #{METER_MEMORY}"
+  # note that if your "test candidate" ruby cannot run the monitor script, then run the benchmark
+  # using the rake of a "stable" ruby, and use the VM parameter.
+
+  a = "#{RUBY_BIN} #{MONITOR} #{TIMEOUT} '#{VM}' #{RUNNER} #{name} #{ITERATIONS} #{report} #{METER_MEMORY}"
+  puts a
+  a
 end

 # Cache the name so it is only generated once during an invocation.
diff --git a/utils/monitor.rb b/utils/monitor.rb
index 5611d55..123b57e 100644
--- a/utils/monitor.rb
+++ b/utils/monitor.rb
@@ -8,7 +8,9 @@ null = "/dev/null"

 require 'rbconfig'
 if RbConfig::CONFIG['host_os'] =~ /mswin|mingw/ # jruby compat.
-  timeout = "ruby " + File.dirname(__FILE__) + "/timeout2.rb"
+  config   = RbConfig::CONFIG
+  ruby_bin = File::join(config['bindir'], config['ruby_install_name']) + config['EXEEXT']
+  timeout = "\"#{ruby_bin}\" " + File.dirname(__FILE__) + "/timeout2.rb"
   null = "NUL"
 end

diff --git a/utils/timeout2.rb b/utils/timeout2.rb
index 61f7033..357c099 100644
--- a/utils/timeout2.rb
+++ b/utils/timeout2.rb
@@ -17,5 +17,8 @@ begin
   }
 rescue Timeout::Error
   puts 'timed out'
-  Process.kill "KILL", out.pid # if this fails it may have died right then
+  Process.kill "KILL", out.pid # if this fails it may have already terminate
+rescue NotImplementedError => e
+  # jruby ... http://jira.codehaus.org/browse/JRUBY-4354
+  puts e
 end