RE: pThreadCreate() in RPGLE

Ron,

Basically, multi-threaded means the job (ie program) is doing multiple
simultaneous tasks.

Good example, a web server.  There's usually a single job (program) running,
for each new request that comes in it will start up a new thread to handle
it.

Threads take less overhead to start than a new job (program). Additional, in
most cases switching between threads is much quicker than switching between
jobs (programs); this is particularly important on non-iSeries platforms.

Here's a link to the multi-thread information in the info-center:
http://publib.boulder.ibm.com/iseries/v5r2/ic2924/info/rzahw/rzahwovepo.htm

You could also google for a considerable amount of info.

HTH,
Charles


> -----Original Message-----
> From: RPower@xxxxxxxxxx [mailto:RPower@xxxxxxxxxx]
> Sent: Wednesday, August 11, 2004 7:41 AM
> To: RPG programming on the AS400 / iSeries
> Subject: Re: pThreadCreate() in RPGLE
> 
> 
> I'm going to ask a n00b question now, but what exactly is multithread 
> program?
> 
> Ron Power
> Programmer
> Information Services
> City Of St. John's, NL
> P.O. Box 908
> St. John's, NL
> A1C 5M2
> Tel: 709-576-8132
> Email: rpower@xxxxxxxxxx
> Website: http://www.stjohns.ca/
> ______________________________________________________________
> _____________
> Success is going from failure to failure without a loss of 
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> Sir Winston Churchill
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> 
> 
> 
> Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx> 
> Sent by: rpg400-l-bounces@xxxxxxxxxxxx
> 10/08/2004 04:48 PM
> Please respond to
> RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>
> 
> 
> To
> RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>
> cc
> 
> Subject
> Re: pThreadCreate() in RPGLE
> 
> 
> 
> 
> 
> 
> 
> Hi Srikanth,
> 
> > Is it possible to create multithreaded programs in RPGLE, 
> some time back
> > I had coded multithreaded programs in C/400 using POSIX 
> APIs (pthread
> > APIs).
> 
> No, sorry.  Unfortunately, RPG programs cannot be 
> multi-threaded.  The RPG
> compiler uses static storage for many of it's internal 
> control structures
> in a manner that is not threadsafe.
> 
> You can call an RPG program from a multi-threaded application 
> by coding
> THREAD(*SERIALIZE) on the H-spec, but it's important to 
> understand what
> that does -- it prevents multiple threads from running the RPG code
> concurrently...  which usually defeats the purpose of making your
> application multi-threaded in the first place ;)
> 
> 
> > I now have do the same but in RPGLE, can I get some helpful links or
> > reference to sample programs. I checked out QUSRTOOL on my 
> box but in
> > vain.
> 
> An alternative might be to use more than one job instead of 
> more than one
> thread -- in this environment, there's no issue with 
> threadsafety.  You
> can use sockets or data queues, etc to synchronize and pass 
> data between
> the jobs.
> 
> There may be other alternatives as well, depending on what you want to
> accomplish with the threads.
> 
> Of course, you can always use Java or C to write a multi-threaded
> application on the iSeries.  Starting in V5R1, C and RPG are 
> part of the
> same package, so if you've got a license to use the RPG 
> compiler, the same
> license lets you use the C compiler.   And Java is free, I believe, in
> OS/400 -- comes with the operating system.
> 
> Good Luck
> 
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