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  1. PO
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    <p>That's a lot of code so I have to confess I didn't read it through, but from what I have skimmed, I think you could take this approach.</p> <p>a) Treat each devices as "actors" i.e. have a single thread which interacts with the actual devices. This thread will read from the devices, and whenever there is an update, submit it to the "manager-service". You may find <a href="http://guava-libraries.googlecode.com/svn-history/r45/trunk/javadoc/com/google/common/util/concurrent/AbstractService.html" rel="nofollow">AbstractService</a> and <a href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ScheduledExecutorService.html" rel="nofollow">ExecutorService.newSingleThreadScheduledExecutor()</a> useful for this. (<code>AbstractService</code> gives you a neat interface on start/stopping device. It'll be excellent for your requirements). Let's call these "device-service".</p> <p>b) Have a "manager-service", which keeps a set of "device-service"s in a collection. "manager-service" should be again an actor, having its own threads (one thread sounds fine from what I read). The executor service in the manager-service will take from its queue the updates from device-services and does whatever necessary (send it, etc.). This queue is populated by the device-services and polled by the manager-service (classic producer/consumer pattern). </p> <p>So, like this:</p> <pre><code>class Manager extends AbstractService { final ConcurrentMap&lt;Device, DeviceService&gt; deviceServices = // blah final ExecutorService exec = // single thread exec //called by API user newDevice(Device device){ DeviceService service = new DeviceService(this,device); deviceServices.put(device,service); service.start(); } //called only by device-services void notifyUpdate(final Device device, final Data data){ Runnable whatever = new Runnable(){ public void run(){ sendStuff.(device.name(), data); } } exec.execute(whatever); } // blah blah blah blah.... // called by API user public void stop(Device device){ deviceServices.get(device).stop(); } </code></pre> <p>and</p> <pre><code>class DeviceService extends AbstractService { final Manager mng; final Device device; final ScheduledExecutorService poller = // single thread DeviceService(Manager mng, Device device){ //blah } // schedule a task that polls device and calls "notifyUpdate" of mng // Whenever there is an update. void start(){ poller.scheduleWithFixedDelay( // poll device, and then call mng.notifyUpdate(device, data) // blah blah blah blah.... </code></pre>
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    1. POJava Concurrency - Better Design approach to manage thread life cycle (start/stop)
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    1. USEnno Shioji
    1. USEnno Shioji
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    1. CO@Jon V, @Enno Shioji:Thanks for the elegant solutions laid out. I'll look into them.
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