Synchronization not working??

[Andrea Darnell]

I am looking for some assistance. I have been playing around with threads and synchronizaton trying to prove that synchronization works, but it doesn't seem to be. I'm using Netbeans 6.5 on Windows Vista (have also tried XP). It's just a simple example. It mixes the thread results up when ran. Since it is sync'd, I wouldn't expect that. Sleep is not supposed to release the lock, but since I am getting bad results, I even tried removing the try/catch block (including the sleep) and I still get mixed up results. I also tried putting a sync'd block right inside the run method, but it still didn't work. Can anyone shed some light on this for me, please? My code is below. Thanks....

    
public class CounterThread implements Runnable {
    public synchronized void run() {
        for(int i = 1; i <= 1000; i++) {
            try {
                Thread.sleep(500);
            } catch(InterruptedException e) {
                System.out.println("I was interrupted");
            }
            if(i % 10 == 0) {
                System.out.println(Thread.currentThread().getName() + " Hitting " + i);
            }
        }
    }

    public static void main(String[] args) {
        new Thread(new CounterThread(), "One ").start();
        new Thread(new CounterThread(), "Two ").start();
        new Thread(new CounterThread(), "Three ").start();
        new Thread(new CounterThread(), "Four ").start();
        new Thread(new CounterThread(), "Five ").start();
    }
}

[arulk pillai]

Don't you want your threads to run in parallel? Why are you synchronizing the run() method?

Check these

-- https://coderanch.com/t/232143/Threads-Synchronization/java/Thread-with-synchronized-run-method

-- https://coderanch.com/t/233751/Threads-Synchronization/java/Any-reason-synchronize-run-method

[Henry Wong]

Can anyone shed some light on this for me, please? My code is below. Thanks....

For two threads to block on each other, they need to synchronize on the same lock. Here you have five different threads synchonizing on 5 different counterthread instances....

Henry

[Andrea Darnell]

This example wasn't really one that made sense. Parallel would be something i would have wanted to do, but I was having trouble with my synchronization, so I started playing with a bare-bones example. Setting up all the threads on the same object fixed it..... Thanks, Henry. It just goes to prove sometimes I just need to smack myself in the face and look at it again. Thanks, again.