Shared object / concurrency

[Rafael Z. Frantz]

Hi folks,

I have an object that is shared by several threads and is an observer. This object has the following methods:

	public void update( Observable arg, Object task ) throws IllegalStateException {
		setChanged();
		notifyObservers( task );
	}

        public void execute() {
                // do something
        }

Considering several threads share this object to invoke the execute() method and that the update() method is receiving thousands of notifications from the observable, do I need to synchronize the code inside mehotd update, like this:

public void update( Observable arg, Object task ) throws IllegalStateException {
		synchronized ( this ) {
			setChanged();
			notifyObservers( task );
		}
	}

Thanks a lot!

[William Brogden]

I certainly would.

Note that there is a lot that could be going on in the Observers, you certainly don't want multiple Threads doing this "simultaneously."

Bill

[Rafael Z. Frantz]

Hi Bill,

I've synchronized and it seems it is working.

Thanks!

[William Brogden]

it seems it is working.

Well thats the tricky thing about multi-threaded programming - it is realllllly hard to test all possible sequences of events for potential collision.

Bill