Threads on DEC Ada for Alpha

Threads on DEC Ada for Alpha

[Marc Peters]

Hello Ada programmers!

I am working on a project which uses DEC Ada on an Alpha. I am working 
on a project where the current design approach is to have several
processes running on different processors. Data that is communicated
between each process is done through "shared memory". I think this is
a more conventional approach that doesn't really utilize the  multi-
threaded nature of OSF/1 running on the Alpha. I am proposing to convert
these separate processes into POSIX threads and have memory shared 
"implicitly". The question I have is has anyone used the DEC Ada
compiler with POSIX threads on the Alpha? If so, do you have any pearls
of wisdom you can share with me about the feasibility of doing this?
The tests I've done so far seem to indicate that it will work fine. 
However, if someone has had problems with this approach, I would be 
grateful to hear from you.

Thanks,
Marc Peters
peters@aisf.com

Re: Threads on DEC Ada for Alpha

[Thierry Lelegard]

On Digital UNIX (new name for DEC OSF/1 :-), the Ada tasks are POSIX threads.
Each Ada task is mapped on one thread. Each time a task is created, the Ada
runtime creates one pthread. So, using pthreads with Ada is natural.

If your software is written in Ada, you have to convert the multi-process
structure in multi-task structure (purely Ada, without pthread programming).
There should be no use for explicit calls to pthreads.

-- 
==========================================================================
Thierry Lelegard, "The Jazzing Troll", Email: lelegard@swthom.enet.dec.com
Digital Equipment France, 9-13 Av. du Lac, 91000 Evry, France    ,,,
Tel: (33) (1) 69 87 68 06, Fax: (33) (1) 69 87 60 65            (. .)
_____________________________________________________________ooO-(_)-Ooo__

Re: Threads on DEC Ada for Alpha

[Simon Wright]

In article <31D28A2D.4C75B287@swthom.enet.dec.com> Thierry Lelegard <lelegard@swthom.enet.dec.com> writes:

> On Digital UNIX (new name for DEC OSF/1 :-), the Ada tasks are POSIX threads.
> Each Ada task is mapped on one thread. Each time a task is created, the Ada
> runtime creates one pthread. So, using pthreads with Ada is natural.
> 
> If your software is written in Ada, you have to convert the multi-process
> structure in multi-task structure (purely Ada, without pthread programming).
> There should be no use for explicit calls to pthreads.

A colleague wasted a _lot_ of time by trying to use Solaris threads
explicitly with SunSoft Ada (Verdix). When he used the features of Ada
(well, actually extensions) designed to hide threads -- specifically,
passive tasks instead of mutexes -- his troubles evaporated.

On a related topic, I see that the "pthreads" in DEC Unix aren't the
same as the "pthreads" used in glibc (from Chris Provenzano) and which
support tasking in GNAT for Linux. However, pthreads-1_60_beta5 builds
and (nearly) works on DEC Unix 3.2 -- not on OSF/1 V3 -- _interesting_
_developments_ are possible! I plan to look into this when the DU 3.2
box gets back from last week's show.

-- 
Simon Wright                    Work Email: simon.j.wright@gecm.com
Ferranti Naval Systems                     Voice: +44(0)1705-701778
GEC-Marconi S3I Combat Systems Division      FAX: +44(0)1705-701800

Re: Threads on DEC Ada for Alpha

[Thierry Lelegard]

Simon Wright wrote:
> 
> On a related topic, I see that the "pthreads" in DEC Unix aren't the
> same as the "pthreads" used in glibc (from Chris Provenzano) and which
> support tasking in GNAT for Linux. 

I do not know what are the pthreads you are talking about. When I write
"pthreads", I mean POSIX threads. Digital UNIX implements native POSIX
threads, without having to install anything. Digital UNIX V4.0 implements
the final standard 1003.1c (1995 standard). Previous versions, up to and
including V3.2, implemented 1003.4a draft 4.

-- 
==========================================================================
Thierry Lelegard, "The Jazzing Troll", Email: lelegard@swthom.enet.dec.com
Digital Equipment France, 9-13 Av. du Lac, 91000 Evry, France    ,,,
Tel: (33) (1) 69 87 68 06, Fax: (33) (1) 69 87 60 65            (. .)
_____________________________________________________________ooO-(_)-Ooo__

Re: Threads on DEC Ada for Alpha

[Simon Wright]

> Simon Wright wrote:
> > 
> > On a related topic, I see that the "pthreads" in DEC Unix aren't the
> > same as the "pthreads" used in glibc (from Chris Provenzano) and which
> > support tasking in GNAT for Linux. 
> 
> I do not know what are the pthreads you are talking about. When I write
> "pthreads", I mean POSIX threads. Digital UNIX implements native POSIX
> threads, without having to install anything. Digital UNIX V4.0 implements
> the final standard 1003.1c (1995 standard). Previous versions, up to and
> including V3.2, implemented 1003.4a draft 4.

The GNAT tasking support implemented for Linux uses a version of POSIX
threads made by Chris Provenzano <proven@mit.edu> which says it is
"based on" 1003.1c 1995.

It is at sipb.mit.edu:/pub/pthreads.

The reason for considering it for DU is that, in all the releases I
have available, the pthreads support doesn't supply what the Linux
GNAT runtime requires. Thanks for letting me know why!

-- 
Simon Wright                    Work Email: simon.j.wright@gecm.com
Ferranti Naval Systems                     Voice: +44(0)1705-701778
GEC-Marconi S3I Combat Systems Division      FAX: +44(0)1705-701800

Re: Threads on DEC Ada for Alpha

[Robert Dewar]

"The reason for considering it for DU is that, in all the releases I
have available, the pthreads support doesn't supply what the Linux
GNAT runtime requires. Thanks for letting me know why!"

The tasking support currently implemented for the DEC Unix port of GNAT
uses the threads support from DEC, not a port of the Provenzano thread
package, or any other separate thread package.

Re: Threads on DEC Ada for Alpha

[Simon Wright]

In article <dewar.836678814@schonberg> dewar@cs.nyu.edu (Robert Dewar) writes:

> The tasking support currently implemented for the DEC Unix port of GNAT
> uses the threads support from DEC, not a port of the Provenzano thread
> package, or any other separate thread package.

Brilliant! Tasking for DEC Unix! I must have missed the announcement
of this - did it come in 3.05?

-- 
Simon Wright                    Work Email: simon.j.wright@gecm.com
Ferranti Naval Systems                     Voice: +44(0)1705-701778
GEC-Marconi S3I Combat Systems Division      FAX: +44(0)1705-701800