Data Noise

We've been using a variation of the exception notification plugin since we deployed our application the first time two years ago and during this time we have fixed almost all bugs just by methodically reacting to every exception email. This plugin is a tremendous help in eliminating bugs! So now whenever we receive a new exception email, that means there is something tricky going on there. That exactly what happened to our production servers, when we misconfigured our DNS server and it took more that 15 seconds to send a single email.

AsyncMailer plugin to the rescue. The bulk of the plugin is below:

    module AsyncMailer
      %w(smtp sendmail).each do |type|
        define_method("perform_delivery_async_#{type}") do |mail|
          Thread.start do
            send "perform_delivery_#{type}", mail
          end      
        end
      end
    end
    class ActionMailer::Base
      include AsyncMailer
    end

where we define two more delivery methods - async_smtp and async_sendmail. The only difference from standard delivery methods is that they are executed in parallel to the main execution and will not effect the ongoing database transaction. There is a chance that the email delivery might fail, but it is not as bad as a missing sale.

If you need to use something like this in your application, here is the link to the source of the plugin, which also includes some cleanup code in case of a process termination signal.

Also it's worth to look at a very nice backgroundrb plugin developed by Ezra Zygmuntowicz. In the future we are going to use it, when we have more long-running tasks to perform. Very great job!