Question

I’d like to have a ScheduledThreadPoolExecutor which also stops the last thread if there is no work to do, and creates (and keeps threads alive for some time) if there are new tasks. But once there is no more work to do, it should again discard all threads.

I naivly created it as new ScheduledThreadPoolExecutor(0) but as a consequence, no thread is ever created, nor any scheduled task is ever executed.

Can anybody tell me if I can achieve my goal without writing my own wrapper around the ScheduledThreadpoolExecutor?

Thanks in advance!

Answer 1

Actually you can do it, but its non-obvious:

• Create a new ScheduledThreadPoolExecutor
• In the constructor set the core threads to the maximum number of threads you want
• set the keepAliveTime of the executor

• and at last, allow the core threads to timeout

  m_Executor = new ScheduledThreadPoolExecutor ( 16,null );
  m_Executor.setKeepAliveTime ( 5, TimeUnit.SECONDS );
  m_Executor.allowCoreThreadTimeOut ( true );
  

  This works only with Java 6 though