CODEWITHSUNDEEP
javamultithreadingtomcatexecutorservice
Jim
Jim

Reputation: 19552

How does the shutdown work in executors?

I have a ScheduledExecutorService and I do a task every 15 mins (in a web application in Tomcat).
In a ServletContextListener in contextDestroyed I have done: 

Runtime.getRuntime().addShutdownHook(new Thread(){  
            @Override  
            public void run(){  
                scheduler.shutdown();   
            }   
        });

The scheduler is started like: 

final Runnable r = new Runnable(){

            @Override
            public void run() {
                System.out.println("My task");
                //Do some task
            }

        };
updater.scheduleWithFixedDelay(r, 30, 15, TimeUnit.MINUTES);

Question:On shutdown any remaining task isn't executed.
There is a task running but I don't see any logs so it seems it is not executed. Why?

UPDATE:
If I start tomcat and then after 2 mins I shutdown then isn't the task considered as scheduled and must run? I mean if a task is submitted isn't it considered as pending? Or it must be actually running?

Upvotes: 1

Views: 336

Answers (2)

Philip Helger
Philip Helger

Reputation: 1864

To explicitly wait until all running tasks are finished, do something like this:

try {
  // Wait for one second indefinitively
  while (!scheduler.awaitTermination (1, TimeUnit.SECONDS)) {
    // wait until completion
  }
} catch (final InterruptedException ex) {
  // interrupted... you may log something
}

Upvotes: 1

Gray
Gray

Reputation: 116828

I can't quite parse your question but maybe your application is not exiting like you'd expect?

Shutting down an Executor will stop any tasks for being submitted but any running tasks will continue to run until they exit. From the shutdown() javadocs:

Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted. Invocation has no additional effect if already shut down.

If you edit your question to be more clear we can answer more appropriately.

Upvotes: 0

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