The :doc:`swf-hello` topic provided a complete implementation of a simple workflow application consisting of a registration application, an activity and workflow worker, and a workflow starter.
Worker classes are designed to run continuously, polling for tasks sent by |SWF| in order to run activities or return decisions. Once a poll request is made, |SWF| records the poller and will attempt to assign a task to it.
If the workflow worker is terminated during a long poll, |SWF| may still try to send a task to the terminated worker, resulting in a lost task (until the task times out).
One way to handle this situation is to wait for all long poll requests to return before the worker terminates.
In this topic, we'll rewrite the activity worker from helloswf, using Java's shutdown hooks to
attempt a graceful shutdown of the activity worker.
Here is the complete code:
.. literalinclude:: swf.java.activity_worker_with_graceful_shutdown.complete.txt
:language: java
In this version, the polling code that was in the main function in the original version has been
moved into its own method, pollAndExecute.
The main function now uses a :javase-ref:`CountDownLatch <java/util/concurrent/CountDownLatch>`
in conjunction with a :javase-ref:`shutdown hook <java/lang/Runtime>` to cause the thread to wait
for up to 60 seconds after its termination is requested before letting the thread shut down.