ADDITIONAL SYSTEM INFORMATION :
runtime: JDK 15
OS: Windows 10
JavaFX: org.openjfx.javafx-base, version 11.0.2

A DESCRIPTION OF THE PROBLEM :
When using javafx.concurrent.Task, opening a connection to a URL prevents the Task thread from closing, even, when the stream is then closed.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
When the Task includes 2 lines opening a stream and closing it, the Task returns correctly. Its `succeed` method runs. **But the Service' `setOnSucceeded` method does not run.** Why?

When the 2 lines about the streaming opening and closing are commented out in the Task, we do get the expected behavior: `System.out.println("in the succeed method of the Service")` does print.

The Main method:

    package Test;
    
    import javafx.application.Application;
    import javafx.concurrent.Worker;
    import javafx.stage.Stage;
    
    public class Main extends Application {
    
        public static void main(String[] args) {
            launch(args);
        }
    
        @Override
        public void start(Stage primaryStage) {
    
            MyService pluginUpdateService = new MyService();
            pluginUpdateService.setOnFailed(e -> {
                System.out.println("task failed");
            });
            pluginUpdateService.setOnSucceeded(e -> {
                System.out.println("in the succeed method of the Service"); // this does not print, when MyTask opens the stream (see code of MyTask)
            });
            // launching the service
            if (pluginUpdateService.getState() == Worker.State.READY) {
                pluginUpdateService.start();
            }
        }
    }

The service `MyService`

    package Test;
    
    import javafx.concurrent.Service;
    import javafx.concurrent.Task;
    
    public class MyService extends Service {
    
        public MyService() {
        }
    
        @Override
        protected Task createTask() {
            Task updater = new MyTask();
            return updater;
        }
    }
The task `MyTask`:
    
    package Test;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.net.MalformedURLException;
    import java.net.URL;
    import javafx.concurrent.Task;
    
    
    public class MyTask extends Task {
    
    
        public MyTask() {
    
        }
    
        @Override
        protected Void call() throws MalformedURLException, IOException {
            InputStream in;
                URL url = new URL("https://clementlevallois.net");
                in = url.openStream(); // when this line is commented out, the Service does trigger its setOnSucceeded method as expected
                in.close(); // when this line is commented out, the Service does trigger its setOnSucceeded method as expected
            System.out.println("about to return from the call method of the Task");
            return null;
        }
    
        @Override
        protected void succeeded() {
            super.succeeded();
            System.out.println("succeeded - sent from the succeeded method of the Task");
        }
    
        @Override
        protected void cancelled() {
            super.cancelled();
            System.out.println("cancelled");
            updateMessage("Cancelled!");
        }
    
        @Override
        protected void failed() {
            super.failed();
            System.out.println("failed");
            updateMessage("Failed!");
        }
    
    }

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The setOnSucceed method of the service should be called
ACTUAL -
The setOnSucceed method of the service is not called.

---------- BEGIN SOURCE ----------
When the Task includes 2 lines opening a stream and closing it, the Task returns correctly. Its `succeed` method runs. **But the Service' `setOnSucceeded` method does not run.** Why?

When the 2 lines about the streaming opening and closing are commented out in the Task, we do get the expected behavior: `System.out.println("in the succeed method of the Service")` does print.

The Main method:

    package Test;
    
    import javafx.application.Application;
    import javafx.concurrent.Worker;
    import javafx.stage.Stage;
    
    public class Main extends Application {
    
        public static void main(String[] args) {
            launch(args);
        }
    
        @Override
        public void start(Stage primaryStage) {
    
            MyService pluginUpdateService = new MyService();
            pluginUpdateService.setOnFailed(e -> {
                System.out.println("task failed");
            });
            pluginUpdateService.setOnSucceeded(e -> {
                System.out.println("in the succeed method of the Service"); // this does not print, when MyTask opens the stream (see code of MyTask)
            });
            // launching the service
            if (pluginUpdateService.getState() == Worker.State.READY) {
                pluginUpdateService.start();
            }
        }
    }

The service `MyService`

    package Test;
    
    import javafx.concurrent.Service;
    import javafx.concurrent.Task;
    
    public class MyService extends Service {
    
        public MyService() {
        }
    
        @Override
        protected Task createTask() {
            Task updater = new MyTask();
            return updater;
        }
    }
The task `MyTask`:
    
    package Test;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.net.MalformedURLException;
    import java.net.URL;
    import javafx.concurrent.Task;
    
    
    public class MyTask extends Task {
    
    
        public MyTask() {
    
        }
    
        @Override
        protected Void call() throws MalformedURLException, IOException {
            InputStream in;
                URL url = new URL("https://clementlevallois.net");
                in = url.openStream(); // when this line is commented out, the Service does trigger its setOnSucceeded method as expected
                in.close(); // when this line is commented out, the Service does trigger its setOnSucceeded method as expected
            System.out.println("about to return from the call method of the Task");
            return null;
        }
    
        @Override
        protected void succeeded() {
            super.succeeded();
            System.out.println("succeeded - sent from the succeeded method of the Task");
        }
    
        @Override
        protected void cancelled() {
            super.cancelled();
            System.out.println("cancelled");
            updateMessage("Cancelled!");
        }
    
        @Override
        protected void failed() {
            super.failed();
            System.out.println("failed");
            updateMessage("Failed!");
        }
    
    }
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
none found. See https://stackoverflow.com/questions/66707119/task-succeeds-but-the-service-onsucceed-method-is-not-triggered

FREQUENCY : always