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Re: How to send a onetime scheduled task to executorService that has a repeptitive task ongoing

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On 03/10/2022 04:32 AM, mike wrote:
> Hi,
>
> We have implemented a "KeepAlive service" that we use over TLS.
>
> This service will send a message every 10 seconds to a server and if we get a response then we are ok and connection is considered ok.
>
> This is started using:
>
> KeepAlive keepAlive = new KeepAlive(this);
>  keepAlive.init();
>             future = scheduledTaskExecutor.newScheduledTask(keepAlive, 0, properties.getKeepAliveTime(),
>                     TimeUnit.SECONDS);
>
> Note: newScheduledTask() calls ScheduledFuture<?> future = executorService.scheduleAtFixedRate(runnable, delay, period, timeUnit);
>
> However we also have a method where we "instantly" want to find out if we are connected to the server.
>
> This is how it looks like:
>
>  public synchronized boolean isConnected() {
>
>         KeepAlive keepAlive = new KeepAlive(this);//create another keepAlive for same session.
>         keepAlive.init();
>
>         if (scheduledTaskExecutor!= null) {
>
>             ScheduledFuture<?> scheduledTaskOnce = scheduledTaskExecutor.newScheduledTaskOnce(keepAlive, 10,
>                     TimeUnit.MILLISECONDS);
>             try {
>                 Object object = scheduledTaskOnce.get();
>                 if (object == null) {
>                     logger.debug("Task has finished! {}", object);
>                 }
>             } catch (InterruptedException | ExecutionException e) {
>                 logger.debug("We could not finished check of connection", e);
>             }
>         return keepAlive.isAlive();
>     }
>
> Note: newScheduledTaskOnce() calls ScheduledFuture<?> future = executorService.schedule(runnable, delay, timeUnit);
>
> Q1: The KeepAlive hangs when doing it as a onetime task in the same executor. Any ideas why?
> Q2: How will a onetime task in same scheduledExecutor be handled when we have a repeatedly ongoing?
>
> br,
>
> //mike
>

Mike,

Without actually running the code or any deep analysis, my first 
reaction to this problem would be to create a single method that does 
one ping when called and exits with a boolean, possibly with a lock so 
only one at a time can run. Then use the scheduler to run it every 10 
seconds and set a static variable that other threads can check. Then if 
you need an immediate test, just call the original method.

hth,
jeff

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How to send a onetime scheduled task to executorService that has a repeptitive task ongoing mike <mikaelpetterson@hotmail.com> - 2022-03-10 04:32 -0800
  Re: How to send a onetime scheduled task to executorService that has a repeptitive task ongoing "Jeffrey H. Coffield" <jeffrey@digitalsynergyinc.com> - 2022-03-10 07:21 -0800
  Re: How to send a onetime scheduled task to executorService that has a repeptitive task ongoing Stanimir Stamenkov <s7an10@netscape.net> - 2022-03-10 22:16 +0200

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