new_mysql2_improvements.rb

require 'mysql2'

module Invoca
  module Mysql2AdapterKillOnTimeout
    def kill(thread_id)
      @connection.query("KILL #{thread_id}")
    end

    def execute(sql, name = nil)

      super

    rescue ActiveRecord::StatementInvalid
      ExceptionHandling.ensure_safe "canceling query for thread id #{@connection.thread_id} - query may still be running" do
        unless active?
          old_thread_id = @connection.thread_id
          reconnect!
          kill(old_thread_id)
        end
      end
      raise
    end
  end
end

module ActiveRecord
  module ConnectionAdapters
    class Mysql2Adapter
      prepend Invoca::Mysql2AdapterKillOnTimeout
    end
  end
end

old_mysql2_improvements.rb

require 'mysql2'
module ActiveRecord
  module ConnectionAdapters
    class Mysql2Adapter
      def kill(thread_id)
        @connection.query("KILL #{thread_id}")
      end

      def execute(sql, name = nil)
        # make sure we carry over any changes to ActiveRecord::Base.default_timezone that have been
        # made since we established the connection
        @connection.query_options[:database_timezone] = ActiveRecord::Base.default_timezone
        if name == :skip_logging
          @connection.query(sql)
        else
          log(sql, name) { non_nil_connection.query(sql) }
        end
      rescue ActiveRecord::StatementInvalid => exception
        ExceptionHandling.ensure_safe "canceling query for thread id #{@connection.thread_id} - query may still be running" do
          unless active?
            old_thread_id = @connection.thread_id
            reconnect!
            kill(old_thread_id)
          end
        end
        raise
      end
    end
  end
end