Rails or Tomcat - which one to be used for background task?


I need advice on a decision that I have to make to decide whether I
should do background task in Rails or in Tomcat.

What I need to do is that a user of web app will create nnumber of text
messages which need to be sent to around 10,000+ users. Sms msg is
passed by the Ruby application to a http server running under Tomcat to
a java application that further passes the msg to sms gateway to be
deliverd to user.
I am planning to put msgs to be sent in a table in mysql by the ruby
application. Now I am not sure which is the reliable and better way to
send the msgs in the background - a background task in ruby or a
backgorund task in java. Also which is the best way to schedule and
start a background job in ruby/rails to handle such a large number of
records to be handled?

Thanks for the help in advance.