public QuartzThreadPool(final int poolSize) {
   checkArgument(poolSize > 0, "Pool size must be greater than zero");
   this.threadPoolExecutor =
       new NexusThreadPoolExecutor(
           poolSize,
           poolSize,
           0L,
           TimeUnit.MILLISECONDS,
           new SynchronousQueue<Runnable>(), // no queuing
           new NexusThreadFactory("qz", "nx-tasks"),
           new AbortPolicy());
   // wrapper for Shiro integration
   this.nexusExecutorService =
       NexusExecutorService.forFixedSubject(threadPoolExecutor, FakeAlmightySubject.TASK_SUBJECT);
 }