Re: threading in rpg. was RPG and Web.. (was Using OO concepts inRPG)

[Hans Boldt <boldt@xxxxxxxxxx>]

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.
>
> Its interesting how the iSeries community accepts the lack of threading and
> event support in the core OS and rpg apps. Esp since with them nuisances
> like locked display sessions can be prevented.  or, while the long running
> display function is running, press a command key to show how much is
> remaining to do.

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.

But then again, threading is more of an issue for systems 
programming, and not for applications programming. Even in systems 
programming, threading isn't really used all that much either. In 
either case, processes are generally easier to deal with than 
threads anyways.

Cheers! Hans