Github user exabrial commented on the issue:
https://github.com/apache/tomee/pull/170
> While this class inherits from ThreadPoolExecutor, a few of the inherited
tuning methods are not useful for it. In particular, because it acts as a
fixed-sized pool using corePoolSize threads and an unbounded queue, adjustments
to maximumPoolSize have no useful effect
need to read the manual better---
