Re: Multithreaded Programming

[Jim Langston <jimlangston@xxxxxxxxxxxxxxxx>]

Yes,

we are talking about the same thing.  Did you see the post I did on
locking of the procedure that is to change memory?

Regards,

Jim Langston

Richard Jackson wrote:
> 
> I don't agree.
> 
> If the subroutines do not use some kind of concurrency control, there is no
> mechanism to serialize access to the variables.  In other words, if two
> threads in the same process execute the code at the same time and the
> initial state of the static variables is given, the final variable state is
> not defined.
> 
> If the code is being executed in two separate jobs, each job has its own
> copy of the variables - there are two sets of variables and the variable
> states are defined but not common.
> 
> Are we talking about the same thing?
> 
> Richard Jackson
> (speaking only for myself)
> 
> -----Original Message-----
> From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
> Behalf Of Jim Langston
> Sent: Wednesday, February 28, 2001 2:31 PM
> To: RPG400-L@midrange.com
> Subject: Re: Multithreaded Programming
> 
> Actually,
> 
> I think building subroutines in a library with static variables would
> do the same thing as a shared named user space.
> 
> Just a though.
> 
> Regards,
> 
> Jim Langston
> 
> Richard Jackson wrote:
> >
> > A strict interpretation of multithreading means that the threads have
> access
> > to each other's variable storage in memory.  Obviously there are controls
> on
> > this sharing.  Your description below is for multi - processes and multi -
> > threads.  Separate processes cannot access each other's variables.  It may
> > not matter to the original requester - but then again it might.  If you
> use
> > separate processes and you want them to share global data, I submit that a
> > shared named user space would be a better solution.  There is a "compare
> and
> > swap" or "test and set" function to control concurrent updating.
> >
> > Richard Jackson
> > (speaking only for myself)
> >
> > -----Original Message-----
> > From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
> > Behalf Of Rich Duzenbury
> > Sent: Wednesday, February 28, 2001 10:42 AM
> > To: RPG400-L@midrange.com
> > Subject: Re: Multithreaded Programming
> >
> > The simplest multithread mechanism I know of is SBMJOB!  Each job can wait
> > indefinitely for it's parameters (using little system resources) by
> waiting
> > for a data queue message.  The parent can then signal the child to start
> > processing by sending a message to the data queue.  Once the thread is
> > complete, the child can end, or if you like go back to waiting for another
> > message.  Global data can be safely shared in a data area or a database
> > record - you just have to be sure to watch your locking.
> >
> > Regards,
> > Rich
> >
> > At 04:02 PM 2/28/01 +0000, you wrote:
> > >Hi All,
> > >
> > >I need some help on creating an application(RPG/CL) which can use
> > >multithreads while running the job.
> > >Can anyone give me some direction with examples.
> > >
> > >thanks in advance,
> > >Ray.
> > >_________________________________________________________________
> > >Get your FREE download of MSN Explorer at http://explorer.msn.com
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