[SOLVED] Problem with threads and ReentrantLock

Newbie & Debugging Questions
#1

I have a problem with a reentrantLock, It never allows other threads to attain it.

The lock it self

private static Lock update = new ReentrantLock();

There is the code I’m using.
[spoiler]


@Override
    public void run(){
        while(Village.running || !scheduled.isEmpty()){               
            
            //Tasks thats need to done
            CoreTask task = getNextTask();
            if(task != null){
                long taskStart = System.nanoTime();
                task.start(); tps++;
                taskTime += System.nanoTime()-taskStart;
            }
            
            //Update the whole game
            long now = System.nanoTime();
            if(update.tryLock()){
                update.lock();
                try{
                    hasLocked = true;
                    delta += (now - lastTime) / (1000000000.0 / Village.targetUPS);
                    lastTime = now;
                    
                    Village.screenUpdate();
                    while(1.0 <= delta){
                        Village.gameUpdate();
                        delta--;
                    }
                    
                    System.out.println("Thread "+getThread().getName()+" is going to sleep.");
                }finally{
                    update.unlock();
                    System.out.println("Thread "+getThread().getName()+" is napping. update is unlocked: "+update.tryLock());
                    try{Thread.sleep(10000);}catch(Exception e){}
                }
            }else{
                System.out.println("Thread "+getThread().getName()+" filed to get the lock");
            }

            if(now-time > 1000000000){
                time = now;
                updateAllCoreInfo();
            }
            
            Thread.yield();
        }//While method ends.
    }//Run method ends.

[/spoiler]

Here is the output

if I remove line 34 to 36 (the else statement) I get this

Why don’t Thread-3 get the lock even when Thread-2 is asleep?

#2

You are doing this:


if(update.tryLock()){
     update.lock();

That’s double locking it. You need to unlock it twice then. Proper usage of tryLock is this:


if (lock.tryLock()) {
  try {
    // do something
  } finally {
    lock.unlock();
  }
}

That should do it!

#3

Thank so much, I thought .tryLock() only tested if it was locked or not

#4

No problem! I’m glad you appreciate my help!

#5

There you go. In case he didn’t get the hint.

#6

oh sorry, I’m kind of new to this site so forgot about that. Sorry

#7

Ha it’s not required or anything.

I suspect it’s secretly a competition and the winner gets a pony or something. So just in case it is, I like to remind people.