Touchstone is a project mainly written in Java, it's free.
simple solr data generator and pusher
touchstone
touchstone is a simple test tool that can generate documents from wikipedia dumps and other random methods and then feed those documents into Solr
Running:
Do not use build.xml - it is not supported currently.
Run from your IDE after linking the touchstone project to a compatible Lucene/Solr project.
main method is in com.lucid.touchstone.Main
usage: wikifile numdocs url {numthreads}
wiki files can be found at http://dumps.wikimedia.org/
JMeter:
There is also a small start at some jmeter plans that match the generated data can be poached from in the jmeter directory.