Because there are unit tests that don't properly shutdown the repository after they finish (e.g. JcrTckTest, ModeShapeTckTest), a large number of threads may "add up" while running the unit tests, due to the fact that their executor services haven't been shut down.

This can be easily observed by running the tests from the modehshape-jcr module and monitoring the JVM in parallel (with jConsole or VisualVM).

The effects can be poor performance or even memory issues (especially when indexing via Lucene)