"ThreadGroup" should not be used

There is little valid reason to use the methods of the ThreadGroup class. Some are deprecated (allowThreadSuspension(), resume(), stop(), and suspend()), some are obsolete, others aren't thread-safe, and still others are insecure (activeCount(), enumerate()) . For these reasons, any use of ThreadGroup is suspicious and should be avoided.

Compliant Solution

ThreadFactory threadFactory = Executors.defaultThreadFactory();
ThreadPoolExecutor executorPool = new ThreadPoolExecutor(3, 10, 5, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(2), threadFactory);

for (int i = 0; i < 10; i++) {
  executorPool.execute(new JobThread("Job: " + i));
}

System.out.println(executorPool.getActiveCount()); // Compliant
executorPool.shutdown();

See

• CERT, THI01-J. - Do not invoke ThreadGroup methods