Re: Seeming Non-determinism in Java Programs

Randall R Schulz wrote:
> On Sunday 06 April 2008 20:07, Stephen Denne wrote:
> > Randall R Schulz wrote:
> > > The queue is
> > > implemented using a heap, though alternatives such as Skip-Lists
> > > are available as options (mostly implemented because of the issue
> > > I'm writing about here).
> >
> > You haven't explicitly mentioned it... but are you using
> > java.util.PriorityQueue?
> 
> No. But I think it's of the same lineage. I originally took 
> it from Doug
> Lea's Heap code and removed the synchronization (it was quite a while
> ago, and I figured the synchronization overhead was not worth it for a
> single-threaded application). Probably nowadays the synchronization
> would not impose a significant / measurable overhead, but at the time
> (java 1.3) that was not so.

For reference, java.util.PriorityQueue javadocs say:

Note that this implementation is not synchronized. Multiple threads should not access a PriorityQueue instance concurrently if any of the threads modifies the queue. Instead, use the thread-safe PriorityBlockingQueue class. 

http://java.sun.com/javase/6/docs/api/java/util/PriorityQueue.html

Regards,
Stephen Denne.

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