I had been running into a lot of issues with Grails running out of heap space on my computer and finally found a solution. In the Grails command line documentation is mentions you can set a maximum heap space when you run grails through the command line. I would keep forgetting to set this and have to restart the app.

export GRAILS_OPTS="-XX:PermSize=128m -XX:MaxPermSize=512m -Xms256m -Xmx512m"
grails run-app

I knew that had to be an easier way, so I created an Environment Variable called GRAILS_OPTS and set the value to

-XX:PermSize=128m -XX:MaxPermSize=512m -Xms256m -Xmx512m -server

Now these settings are used anytime I run grails.