RE: RPG IV Performance

Lisa,

re: size

Just for giggles I took one of the significant RPG III programs from the
package that we use and tried compiling it several ways, then converted it
with the CVTRPGSRC command and compiled that several ways.  The sizes I got
were:

RPG III with 2207 lines of source code:
with no optimization and no source debug info - 565,248 bytes
with no optimization and *LSTDBG info -         978,944 bytes
with *OPTIMIZE and no source debug info -       516,016 bytes

RPG IV with 2250 lines of source code:
with no optimization and DBGVIEW(*NONE) -       720,896 bytes
with no optimization and DBGVIEW(*ALL) -      1,499,136 bytes
with OPTIMIZE(*FULL) and DBGVIEW(*NONE) -       688,128 bytes

I did NOT try removing observability, nor did I try compressing the
programs.  Yes, the RPG IV is a little bigger, but less than 2x the
comparable RPG III versions.  Smaller programs than this one might show a
larger percentage difference, but 10x strains my credulity.  I didn't try
any benchmarking, but I've never seen an RPG IV program performing
noticeably worse than its RPG III equivalent, unless it was called
frequently with ACTGRP(*NEW) (tried that once for fun, never had it in
"real" life).  The difference in size might make a difference on a system
that's extremely memory-constrained, if you had a lot of programs suddenly
grow (not just one).  This is only theory, though, I've never seen it
happen.

Anyway, I am very skeptical of his claims, since they don't match my
experience.

Dave Shaw
Spartan International, Inc.
Spartanburg, SC
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-----Original Message-----
From: Lisa.Abney@universalflavors.com

Hi all!  I've just heard some rather negative performance things on RPG IV,
and
wonder if anyone can give me some feedback on how true this might be.

We're working with a consulting company who is doing some performance
analysis
on some of our programs.  They seem very knowledgeable, and I have a lot of
confidence in what they've done up until now.  However, today they were
showing
us a mock-up of a trigger program they want to use.  As they explained it,
this
trigger program will be constantly running in the background for every user
on
the system to monitor changes to two files, and will feed data to a dataque.
The program they showed me was written in RPGIII, and I made my usual
request to
an outside contractor that this be done in RPGIV.  His response was "Sure,
if
you want the program size to be 5 - 10 times the size of an RPGIII program."
When I asked him to explain that, he only said that, in his experience, this
is
always true, and that it would have a very negative performance.  I even
mentioned removing observability (not that I really understand what that
means,
but I just read something the other day about that being a way to reduce
program
size!), and he said that might move it down to 3 - 5 times the size of an
equivalent RPGIII program.  The program will only be about 50 - 100 lines of
code.

Can someone explain if this is true, and, if so, why?  And, if true, what
does
this really mean from a performance standpoint?
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