Testing MRI threads with ActiveRecord's sql server driver. Shows the sql server driver blocks on IO under MRI.

gistfile1.rb

#! /usr/bin/env ruby
# Adapted from slide 5 at http://www.slideshare.net/igrigorik/no-callbacks-no-threads-railsconf-2010
 
require 'bundler/setup'
require 'active_record'
require 'tiny_tds'
require 'active_record/connection_adapters/sqlserver_adapter'
 
ActiveRecord::Base.establish_connection(
  :adapter => 'sqlserver',
  :host => 'localdb',
  :database => 'some_datarbase',
  :username => 'sa',
  :password => 'youknowit',
  :timeout => 1500,
  :pool => 10 
)
 
stime = Time.now
 
threads = []
10.times do |n|
  threads << Thread.new do 
    ActiveRecord::Base.connection_pool.with_connection do |conn|
      # Block connection for one second.
      res = conn.execute("WAITFOR DELAY '00:00:10'")
    end
  end
end
 
  
threads.each do |t|
  begin
    t.join
  rescue Exception => e
    puts "Exception in thread: #{e.class}"
  end
end
 
puts "\n\nElapsed real time: #{Time.now - stime} seconds"
 
# On my computer:
#
# * mysql:  10.19 seconds, as expected for broken mysql adapter that holds onto
#   ruby GIL 
#
# * mysql2 with either ruby 1.8.7 OR ruby 1.9.2: 2.1 seconds 
#   (still surprisingly more than the 1s and change expected. still a lot of 
#    overhead from  context switching and/or connection pool checkout? 
#    But not as disastrous as 'mysql'