Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!gatech!hubcap!braner
From: braner@tcgould.tn.cornell.edu (Moshe Braner)
Newsgroups: comp.parallel
Subject: Re: Linda: specific sharing vs. generative communication
Summary: Linda is not "too abstract"
Message-ID: <5423@hubcap.clemson.edu>
Date: 8 May 89 12:02:25 GMT
Sender: fpst@hubcap.clemson.edu
Lines: 25
Approved: parallel@hubcap.clemson.edu

[responding to the claim that Linda enforces excessive abstraction]

With Chares: parent process tells child it's ID, child is programmed
send return result to that destination (the parent).

With Linda: parent process looks for result with a specific tag, e.g.,
a specific string in the first element of the tuple.  Child is programmed
send return result in a tuple with that tag.

I don't see how Linda is restrictive there.  In fact, it is less restrictive,
but easily allows what is needed here.  The tag, suitably chosen, can make
the program more readable.  The fact that the tuple is put into a common
space allows a debugger to examine it before the parent gets it.  Etc.

As for efficiency, only actual benchmarks can tell.  All the approaches
for global data are easier to implement on shared-memory machines, of
course.  It's tough with distributed memory, and will always be less
efficient than straight message-passing.  But the goal is (for some of
us, anyway) an 80%-efficient application created and maintained with
one-third the human work as compared with the 90%-efficient optimized
implementation...

- Moshe

Exclaimer:  Wow!