Bookies are individual BookKeeper servers. You can run an ensemble of bookies locally on a single machine using the
localbookie command of the
bookkeeper CLI tool and specifying the number of bookies you'd like to include in the ensemble.
This would start up an ensemble with 10 bookies:
$ bookeeper-server/bin/bookeeper localbookie 10
When you start up an ensemble using
localbookie, all bookies run in a single JVM process.