Configure JRuby runtime pool on GlassFish gem

$ glassfish -n 3 --runtimes-min 2 --runtimes-max 4

The above dcommand will run the Rails or any Rack based Ruby application with 3 JRuby runtimes, the hard minimum of the pool will be 2 and that hard maximum will be 4.

-n --runtimes NUMBER:   Number of JRuby runtimes to create initially

--runtimes-min NUMBER:  Minimum JRuby runtimes to create

--runtimes-max NUMBER:  Maximum number of JRuby runtimes to create