Re: JavaMemoryModel: october JMM spec seems to break java's threading model

From: Jerry Schwarz (
Date: Fri Nov 07 2003 - 15:00:41 EST

At 11:13 AM 11/6/2003, Joe Hendrix wrote:
>Doug Lea wrote:
> > The best you can say is "over sufficiently long
> > observation periods, unblocked threads will progress"
>Will all unblocked threads make progress? A common fairness guarantee
>in model checking literature would be that if a thread can infinitely
>often make progress (e.g it is unblocked and perhaps has the highest
>priority), then it will infinitely often make progress or terminate.
>There isn't any guarantee in timing, just that eventually each
>unblocked thread will make progress.
>Do existing JVMs provide this guarantee?

No. At least one JVM I'm aware of is totally non-preemptive. If one thread
starts executing

     while (true) ;

No other thread ever runs.

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