Re: JavaMemoryModel: How about "Synchronizes to" and "Synchronizes from"

From: Victor Luchangco (Victor.Luchangco@Sun.COM)
Date: Fri Mar 26 2004 - 11:17:25 EST

Bill Pugh wrote:
> We've discussed needing some phrase we can use instead of
> "creates a happens-before edge" in places such as
> Javadoc.
> One proposal was "Synchronizes with", but I don't like that because
> it sound symmetric, and doesn't convey the directed nature of
> synchronization.
> So what do you think about "synchronizes to" (and "synchronizes from")?
> For example,
> starting a thread synchronizes to the run method of the thread
> successful joining with a thread synchronizes from the run method of
> the thread
> -------------------------------
> JavaMemoryModel mailing list -

I dislike the use of "to" and "from" with synchronized. It sounds
unnatural to me, and I wouldn't know what it meant. I can easily
infer the meaning in this case, but that's no better than using
"synchronized with", which at least sounds better.

Did we decide that using "happens-before" (with hyphen) was too
subtle and likely to be missed?

   starting a thread happens-before the run method of the thread

(Of course, that would not give us the inverse relation without
another definition. But we could define happens-after to be that

If the desire is to avoid sounding too technical, then perhaps:

  starting a thread must occur before the run method of the thread
  successful joining with a thread must occur after the run method...

In all the above examples, I think "the run method" should really
be replaced with a specific event, e.g., "starting a thread must
occur before the invocation of the run method..."

If retaining "synchronized" is important, then perhaps we can say

   starting a thread is synchronized before the invocation of ...
   successful joining with a thread is synchronized after ...

The main objection I have to this last version is that "synchronized"
implies a similarity in time, so "synchronized before/after" is an
oxymoron of a sort. Of course, we are using the term in a technical
sense, so we can have it mean whatever we want. But using that
reasoning, I think we should just revert to using the technical
happens-before relation.

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