From: kempson@ICSI.Berkeley.EDU (Mark Kempson)
Newsgroups: ba.seminars
Subject: 4/15/92 Heinz Schmidt Talk at ICSI
Keywords: Towards Data-Parallel Object-Oriented Programming
Date: 7 Apr 92 18:44:47 GMT
Article-I.D.: agate.rsqivINNbr9
Distribution: ba
Organization: International Computer Science Institute, Berkeley, CA, U.S.A.
NNTP-Posting-Host: icsid.icsi.berkeley.edu


              The International Computer Science Institute
                     is pleased to present a talk:

                 Wednesday, April 15, 1992  11:00 a.m.

                           HEINZ W. SCHMIDT
                CSIRO Division of Information Technology
                          Canberra, Australia

         ``Towards Data-Parallel Object-Oriented Programming''

           Data parallelism provides a form of implicit  parallel-
      ism  in  which  elements of collections operate virtually in
      parallel. So far it has been  proven  a  simple,  clear  and
      powerful  programming  paradigm for SIMD architectures. This
      talk considers a data parallel extension for Sather, a stat-
      ically typed object-oriented language initially designed for
      virtually shared-memory MIMD machines.

           Programming massively parallel computers is  a  complex
      task  because  our  semantical models, programming languages
      and tools are not up to the task. Massively parallel comput-
      ers are multi-processors consisting of thousands of physical
      or virtual processing elements. Massively parallel  process-
      ing can still increase performance by several orders of mag-
      nitude. However, software development for  these  processors
      is  a major bottleneck, as the software is most often archi-
      tecture dependent,  non-portable,  and  therefore  extremely
      short-lived.

           One view of  object-oriented  programming  is  that  it
      removes  most  of  the  case statements of traditional high-
      level programs, thus cutting down the need to modify  exist-
      ing  modules  when the programs are extended.  In analogy to
      this observation, we view  data-parallel  programming  as  a
      technique  removing  most  of the loops of traditional high-
      level programs, thus simplifying porting and  adapting  pro-
      grams  to  different  parallel architectures. How is ``loop-
      less looping'' possible?  We develop a  view  of  collection
      types  as  bulk data types supporting higher-order functions
      like mappings and reductions  that  virtually  ``propagate''
      messages  to  the collection elements. These messages invoke
      user-defined methods on these more elementary data or  rear-
      range  the  collections  to  improve  subsequent  collection
      operations.  Barrier synchronization  at  the  end  of  such
      method  executions allows an implementation of this model on
      modern MIMD machines like the Fujitsu CAP or the CM-5.

           A number of interesting  and  still  unsolved  problems
      arise  in  the context of strong typing and efficient imple-
      mentations of bulk data types.

        This talk will be held in the Main Lecture Hall at ICSI.
          1947 Center Street, Sixth Floor, Berkeley, CA 94704
       (On Center between Milvia and Martin Luther King Jr. Way)
Newsgroups: ba.seminars