title: Additional thread pools within Tomcat apps
body: <p>I work with a Java webapp that runs with Apache Tomcat. The max threads for the Tomcat thread pool is 800, and the minSpareThreads is 25. While it runs, it usually sits at around 400 running threads at a given time.</p>
  <p>Let's say I have a computationally expensive, non-blocking task that I have to do in my Tomcat app, in which the ForkJoinPool.commonPool is used to solve the task more efficiently.</p>
  <p>Because my Apache Tomcat app already has a large thread pool in it, does the Tomcat thread pool reduce the performance gains I would get from using a ForkJoinPool (or any thread pool, for that matter) in my Tomcat app? Could the performance costs of running the Tomcat threadpool along side a ForkJoinPool negate the performance gains of using a ForkJoinPool because now, there are going to be way more threads than there are CPUs?</p>
  <p>Is adding any sort of additional thread pool to an Apache Tomcat app bad for the performance of the entire application?</p>