Add a threaded example as well

examples/threaded.rb

@@ -0,0 +1,20 @@
+# encoding: utf-8
+
+$LOAD_PATH.unshift 'lib'
+require 'mysql2'
+require 'timeout'
+
+threads = []
+# Should never exceed worst case 3.5 secs across all 20 threads
+Timeout.timeout(3.5) do
+  20.times do
+    threads << Thread.new do
+      overhead = rand(3)
+      puts ">> thread #{Thread.current.object_id} query, #{overhead} sec overhead"
+      # 3 second overhead per query
+      Mysql2::Client.new(:host => "localhost", :username => "root").query("SELECT sleep(#{overhead}) as result")
+      puts "<< thread #{Thread.current.object_id} result, #{overhead} sec overhead"
+    end
+  end
+  threads.each{|t| t.join }
+end