LOOM (was: Delegation and ...)

Jecel Assumpcao Jr jecel at merlintec.com
Thu Aug 23 17:17:44 UTC 2001

On Wednesday 22 August 2001 22:46,  Stephen Pair wrote:
> > I mentioned on the Squeak list some designs I have considered over
> > the
> > years for this. I don't think a consumer quality system is possible
> > without it. Things are simply not automatic enough.
> I'd be interested in hearing those designs...I'm working on a design
> myself...

Well, it probably isn't worth cross posting here. I am not sure whether 
the thread should go on in the Squeak list either (in the thread 
"[Cross-space references] NewtonOS and Sessions"). BTW, I'll answer 
here a question you made there -

> Would this work?  Has it been done before?

Ian Piumarta is the right guy to ask about this. See


There are other projects at SOR that are related to this as well.

> I've been reading the Kaehler's LOOM stuff and that's been
> very helpful in identifying the things I need to watch out for. 

Though LOOM was created to eliminate the problems with OOZE, it is 
worth knowing that system as well.

   "Virtual Memory for an Object-Oriented Language"
  by Ted Kaehler
  pages 378 to 387 in Byte Magazine, August 1981, Volume 6 Number 8

> I'm
> shooting for something that will make incremental persistence fast,
> and will provide a commit primitive that will ensure everything is on
> disk.  Looks like the LOOM design would be expensive if you want to
> make sure everything was saved (requiring a scan of object memory I
> think).

You must scan the whole object table and flush any "dirty" objects back 
to disk. This is normally done in the background continuously, but you 
might have to force a full scan in order to commit.

I would consider the system created for the Mushroom project to be an 
evolution of LOOM:


See the garbage collection papers, specially the last one.

> Actually, I'm amazed that this hasn't been a higher priority with
> SqC...you really can't consider Squeak as an OS without a solution in
> this area.  And, it's been done in so many other contexts...why not
> Squeak?  Makes me wonder if there's something I'm missing?

Too many virgin PhDs have been sacrificed to this dragon for them to 
undertake such a project lightly. I wouldn't say it has ever been done 
*right* in any other context.

-- Jecel

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