Re: JavaMemoryModel: PC language alert: catatonia action

From: Jerry Schwarz (jerry.schwarz@oracle.com)
Date: Sun May 16 2004 - 16:30:05 EDT


At 06:14 PM 5/15/2004, Jeremy Manson wrote:
> > I do think that both "catatonia" and "reclusive" sound rather unpleasant.
> >
> > I may be missing something, but isn't the term "silent action" or "tau
> > action" commonly used for this? See e.g. the literature on the pi-calculus.
>
>I believe that "silent actions" and "tau actions", like SKIP in CSP, don't
>do anything. A catatonia action requires that the thread perform nothing
>but catatonia actions thereafter.
>
>My own thoughts are along the lines of "sleep", or "suspend". I think
>"sisyphean action" has a nice ring to it, but people don't like semantics
>to have a nice ring to them.

In general it's undecidable whether a thread will ever issue any more (non
catatonic) actions.
So I wonder what would depend on it? Is this another attempt to say
something about fairness?

Certainly a compiler noticing that at some point code is going into an
infinite loop that does nothing could replace the infinite loop with some
kind of "suspend". But I hope we can justify that as an optimization of the
normal semantics without resorting to discussing any special actions.

By the way. I think Lamport calls actions that do nothing "stuttering".

> Jeremy
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