RE: threading in rpg. was RPG and Web.. (was Using OO conceptsin RPG)

Steve,

I've heard (here and there) that MUTEX is a kludge that doesn't perform all
that well for serialized access.  I really don't think RPG is going to play
nice in this regard, and you'd probably be better off looking to Java or C++
for multithreaded languages.  JMO...

Eric DeLong
Sally Beauty Company
MIS-Project Manager (BSG)
940-898-7863 or ext. 1863



-----Original Message-----
From: Steve Richter [mailto:srichter@xxxxxxxxxxxxx]
Sent: Tuesday, May 20, 2003 10:11 AM
To: RPG programming on the AS400 / iSeries
Subject: RE: threading in rpg. was RPG and Web.. (was Using OO concepts
inRPG)



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Hans Boldt
Sent: Thursday, May 15, 2003 2:36 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Re: threading in rpg. was RPG and Web.. (was Using OO concepts
inRPG)


Steve Richter wrote:
> I am curious to know what limitations RPG has with respect to threading.
I
> know very little re: threading on the iSeries.
>

Hans replied:
>There are a number of global data structures used internally in RPG
>programs, which makes RPG programs non thread-safe. For example, on
>a program exception in one thread, you'd get some global areas
>updated which could affect the execution of another thread. To make
>RPG programs thread-safe would require giving each thread it's own
>set of internal data structures, which is not a trivial task. And it
>could very well be impossible without changing certain fundamental
>aspects of RPG program semantics.


Can I still ask about this?  Its important because there are ways to design
web applications that can capitalize on threading ( as the browser user
bounces around from page to page on your site, run a new thread each time
the user jumps out of the normal page driven flow of the site ).

Serializing access to common internal data structures of an rpg pgm can be
handled by a mutex, no?  In Win32 there are a series of CriticalSection APIs
that are made to handle these threading issues.  This way, each thread does
not need its own set of internal data structures. All the threads share the
same data and use mutexs to serialize access.

thanks,

Steve


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