Memory requirement for JRuby deployment?

So we’re trying to deploy our first JRuby app. We have a 256mb
accelerator at Joyent.

We couldn’t install Glassfish - not enough memory. So then we tried
Jetty, which we got installed, but can’t get running.

So are we pushing our luck with only 256mb for RAM. I really don’t want
to go back to Mongrel :frowning: