Playing around with massive numbers of derby databases.
$ export MAVEN_OPTS="-server -Xmx10G"
$ mvn clean install jetty:run -Dderby.system.home="$(pwd)/target/classes"
$ for i in $(seq 1 4000) ; do printf "curl -v -H \"tenant: tenant%s\" http://localhost:8080/\0" "$i" ; done | parallel -0