Java Thread stops without Exception/Throwable

Question

I've a very annoying problem and I'm not able to fix this by myself.

I have a simple JavaFX Scene with just 2 buttons for start and killing the thread. The stop-action is not relevant in this case because I'm not able to get the thread working well. The actionListener looks like:

EDIT1: Figured out the problem, it's not thread specific, it's the request against the TimeServer, take a look here: answer
Thanks to everyone of you who answered this or read the question! :)

private FarmAction action = null;

@FXML
void btnStartListener(ActionEvent event) {      
Firefox ff = new Firefox();
ff.startBrowser();

BrowserAction browserAction = new BrowserAction(ff.getDriver(), ff.getJse());
browserAction.loginToGame(user, pass);
ObservableList<AttackCommand> list = (ObservableList<AttackCommand>) Serializer.deserialize(Constants.FILE_NAME_TESTPURPOSE);


if(action == null)
    action = new FarmAction(ff.getDriver(), ff.getJse(), list);

Thread run = new Thread(action);
try {
    run.start();
} catch (Exception e) {
    e.printStackTrace();
} catch (Throwable t) {
    t.printStackTrace();
 }
}   

Note: I'm working with the Selenium Framework to automate some clicks on a Website.

My FarmAction class looks like this:

public class FarmAction implements Runnable{

private WebDriver driver;
private JavascriptExecutor jse;
private ObservableList<AttackCommand> attackList;
private boolean stop = false;

public FarmAction(WebDriver driver, JavascriptExecutor jse, ObservableList<AttackCommand> attackList) {
    this.driver = driver;
    this.jse = jse;
    for(AttackCommand ac : attackList)
    {
        ac.transferFromPropToAttributes();
    }
    this.attackList = attackList;
}


@Override
public void run() {
    ArrayList<Integer> unitIds = Constants.UNIT_ID_LIST_ALL;
    if(!driver.getCurrentUrl().equals(Constants.URL_TESTPURPOSE))
            driver.navigate().to(Constants.URL_TESTPURPOSE);
    int count = 0;
    while(true) { // Just let the Thread run for duration = lifetime of application
        System.out.println(count++); //count how often the thread runs into this while loop before terminating for no reason
        for(AttackCommand ac : attackList) {            
            for(int i = 0; i < unitIds.size(); i ++) {
                int unitKey = unitIds.get(i); // Momentane UnitID der Iteration                 
                if(ac.getUnits().containsKey(unitKey) && ( ac.getTurnBackTime() == 0 ||ac.getTurnBackTime() <= DateUtil.getActualServerTime())) // getActualServerTime is request against the timeserver de.pool.ntp.org
                {
                    String textfieldName = Constants.HASHMAP_TEXTFIELD_NAME_ALL_HTML_PLACE.get(unitKey);
                    WebElement textfield = driver.findElement(By.name(textfieldName));
                    textfield.sendKeys(String.valueOf(ac.getUnits().get(unitKey)));

                    WebElement textfieldCoordinates = driver.findElement(By.name(Constants.TEXTFIELD_NAME_HTML_PLACE_COODRINATESFORTARGET));
                    textfieldCoordinates.sendKeys(StringHelper.getPointAsString(new Point(ac.getXCoordinates(), ac.getYCoordinates())));


                    WebElement submitButton = driver.findElement(By.id(Constants.TA));
                    submitButton.click();

                    WebElement sndAttackSubmitButton = driver.findElement(By.name(Constants.SBM));

                    WebElement span = driver.findElement(By.className(Constants.CLASSNAME_TIME));
                    long duration = Long.parseLong(span.getAttribute(Constants.ATTRIBUTE_DURATION));

                    sndAttackSubmitButton.click();
                    ac.setStartTime(DateUtil.getActualServerTime());
                    ac.setDurationInSeconds(duration*1000);
                    ac.setTurnBackTime(ac.getStartTime()+ac.getDurationInSeconds());
                } 
            }
        }
    }
}}

As you see I've wrapped the Thread.start() method into a try-catch for Throwables AND Exceptions but I don't get any Stacktrace if the thread stops for no reason. I expected an StackOverFlow Error but I don't catch anything.

The amount of loops my thread is working is very different. Sometimes it stops after 12, then other times after 370 or 59. All values are examples - it's different each time.

Do you have any Ideas what I'm doing wrong?

Thanks in advance!

Answer 1

OK guys, I've figuered the problem out. It's not thread specific, sorry for that, but I've learned almost a bit more about threads because of your answers :) Thanks to everyone of you!

I've put SystemOuts behind every single codeline and figured out after 25 runs and freezes there are two possible codelines where thread stops working:

Both statements use my DateUtil.getActualServerTime() Method which looks as follows: ​

public static long getActualServerTime() {
    String TIME_SERVER = "de.pool.ntp.org";   
    NTPUDPClient timeClient = new NTPUDPClient();
    InetAddress inetAddress;
    long returnTime = 0;

    try {
        inetAddress = InetAddress.getByName(TIME_SERVER);
        TimeInfo timeInfo = timeClient.getTime(inetAddress);
        returnTime = timeInfo.getMessage().getTransmitTimeStamp().getTime();
    } catch (Exception e) {
        e.printStackTrace();
    } catch (Throwable t) {
        t.printStackTrace();
    }

    return returnTime;
}

I'm using the apache.commons.net lib for that. If I'm just return a Date d = new Date(); return d.getTime(); my thread works fine for about 60.000 loops until I've stopped it manually.

I don't get an Exception or Throwable here as well. I'd say theres a maximum amount of request against the time server in a specific time or something like that. I can't figure it out on the Website right now.