install apache ab

change database.yml (just so it doesn't error - don't need a db)

deploy your app to glassfish (jruby -S warble && asadmin deploy thread_test.war)

cd into app directory and
ab -p post_file.txt -n 10 -c 3 
http://<your_glassfish_server>/thread_test/thread_test/test?data=aklsjdfakjsdfalkjsdflkasdjflkasjdflksj

you will notice that between 1-2 requests will have a nil request.raw_post