Question

I developed a program which after every two minutes call db to check new tasks

public static void main(String[] args) {
ScheduledExecutorService scheduler =     Executors.newSingleThreadScheduledExecutor();
scheduler.scheduleWithFixedDelay(new ESMSCampaignTask(), 0, 2, TimeUnit.MINUTES);
}

Now following code check from DB and execute threads

public void run() {

    ExecutorService execService = Executors.newFixedThreadPool(5);

    List<ScheduledCampaigns> scheduledCampaignsList =   campaignsService.getScheduledCampaigns();

    for (ScheduledCampaigns campaign : scheduledCampaignsList) {

        String cmpName = "SCH_CAMPAIGNS_" + campaign.getCampaign_id();

        execService.execute(new Runnable() {
            public void run() {
                smppService.submitShortMessage(campaign);
            }
        });

    }//EO For Loop

}//EO Run

The solution i am looking for is that how i can get status of completion of above threads so that i update DB accordingly?

I tried to execService.awaitTermination(500, TimeUnit.SECONDS);

But i would not be able to start new threads until existing threads finish their task.

So solution should provide such functionality that i could be able to start new threads after every two minutes without waiting for existing threads completions and meanwhile i keep on getting status of threads completion so i update database accordingly.

Regards,

Answer 1

If you use ExcecutorService.submit() rather than execute, you can get a Future object.
Store this in a vector, and you can then loop through the items in this vector to check on their completion state.;

/**  keep track of currently running tasks */
Vector runningTasks<Future> = new Vector<Future>();

public void run(){
  for (ScheduledCampaigns campaign : scheduledCampaignsList) {

    String cmpName = "SCH_CAMPAIGNS_" + campaign.getCampaign_id();

    Future f = execService.submit(new Runnable() {
        public void run() {
            smppService.submitShortMessage(campaign);
        }
    });
    runningTasks.add(f);

  }//EO For Loop

  // which tasks have just completed?
  Vector<Future> justCompletedTasks = new Vector<Future>();

  // check currently executing tasks
  for (Future task : runningTasks){
   if( task.isDone() || tasks.isCancelled() ){
      justCompletedTasks.add(task);
   }
  } // EO check executing tasks

  // remove completed tasks from current list
  runningTasks.removeAll(justCompletedTasks);
} // EO run

Sorry this is untested, but hope the idea is useful?