The DBDA2E programs have been updated so they deal better with parallel chains in runjags and the number of cores available on your computer. The new programs are available as this zip folder also linked at the book's software page. There are 29 modified programs. They check for the number of cores on the computer and set the number of chains and the runjags method appropriately (I hope!).
Thanks go to reader Christoph Schmid, affiliated with Universität Regensburg, for notifying me of an error that instigated me to modify the programs.
AND there is a new version of runjags available! It has many new features.