Re: OOPLs and Locality of Reference

From: (Mario Wolczko)
Keywords: locality of reference
Date: 5 Jul 93 14:39:13 GMT
Organization: Dept Computer Science, University of Manchester, U.K.

The measurements done as part of the work here on the Mushroom project
show that temporal locality within Smalltalk objects is great (and
hence even conventional caches work reasonably well [unless the GC
scheme trashes the cache]), whereas spatial locality on a scale much
larger than the average object (which is 40 bytes) is much harder to
come by.

More details can be found in these papers (all available by ftp from in /pub/mushroom/papers):
    "Dynamic Grouping in an Object Oriented Virtual Memory Hierarchy"
    Ifor Williams, Mario Wolczko, Trevor Hopkins, Proc. ECOOP 87,
    Springer-Verlag LNCS 276, pp.79-88.
    "Realization of a Dynamically Grouped Object-Oriented Virtual
     Memory Hierarchy", Proceedings of the Workshop on Persistent Object
     Systems: Their Design, Implementation and Use, available as
     Persistent Programming Research Report PPRR-44-87, Universities
     of Glasgow and St. Andrews, Aug. 1987, pp.298--308.
    "An Object-Based Memory Architecture"
    Ifor Williams and Mario Wolczko, in Implementing Persistent Object
    Bases: Proc. Fourth International Workshop on Persistent Object Systems,
    Morgan Kaufmann, 1991, pp.114-130.
    The first three figures are in obma-fig[123].ps.Z.

Mario Wolczko

   ______      Dept. of Computer Science   Internet:
 /~      ~\    The University              uucp:    mcsun!uknet!man.cs!mario
(    __    )   Manchester M13 9PL          JANET:
 `-':  :`-'    U.K.                        Tel: +44-61-275 6146  (FAX: 6236)
____;  ;_____________the mushroom project___________________________________

>34  Pred Classes (Cecil)

What: "Predicate Classes" paper
From: (Craig Chambers)
Date: Fri, 30 Apr 93 01:25:02 GMT

"Predicate classes are a new linguistic construct designed to
complement normal classes in object-oriented languages. Like a normal
class, a predicate class has a set of superclasses, methods, and
instance variables. However, unlike a normal class, an object is
automatically an instance of a predicate class whenever it satisfies a
predicate expression associated with the predicate class. The
predicate expression can test the value or state of the object, thus
supporting a form of implicit property-based classification that
augments the explicit type-based classification provided by normal
classes. By associating methods with predicate classes, method lookup
can depend not only on the dynamic class of an argument but also on
its dynamic value or state. If an object is modified, the
property-based classification of an object can change over time,
implementing shifts in major behavior modes of the object. A version
of predicate classes has been designed and implemented in the context
of the Cecil language."

Comments on the ideas in the paper are appreciated.

-- Craig Chambers

>35  Manchester Archive and some

What: Manchester Archive, SmallTalk-V
From: (Ralph Johnson)
Date: 18 Dec 91 19:41:38 GMT

We have a complete copy of everything in the Manchester archive, and you
can either access it by e-mail like the Manchester archive or by anonymous
ftp.  Our archive is on, and you can get information about the
e-mail server by sending to, and putting the
line help in your message. We actually have a little more than is in the
Manchester archive.  We have the Smalltalk-V code from the defunct
International Smalltalk Association, and a few other odds and ends.

>36  Object Design's OO7 Results

What: Object Design's Results on the OO7 Benchmarks
From: (Glen Dudek)
Date: Thu, 29 Apr 93 17:17:11 GMT

April 26, 1993

We have made a copy of our results available to the Internet community. You
can access this information through anonymous ftp from in the
file /pub/oo7/

The report includes the "official" tests done for ObjectStore by the
University of Wisconsin, and our internal execution of all the tests using
ObjectStore Release 2.0.1, the current production version.  As the report
shows, our internal execution carefully followed the agreed-upon procedures
for running OO7, and we believe the numbers that were produced accurately
represent ObjectStore's performance.

        For further information contact

>37  Graph service
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