Stardust is a hack consisting of a D3 sunburst visualization and a little dirty parser for Java thread dumps.
Everything is contained in the index.html file so you just load that on a webserver and view the page in your browser - Chrome is preferred. You can also try it out at here.
Once the page is loaded find one or more thread dumps - generated via jstack <pid> > threads.log - and drag the files onto page. No files will be uploaded as the parsing and rendering happens on the page itself.