Re: Occam vs. monitor

[Denis A Nicole <D.A.Nicole@xxxxxxxxxxxxxxx>]

On Tue, 26 May 1998, phw wrote:

> 
> Oyvind,
> 
> > Does this hold water:
> > 
> >   Occam's communication language primitives cannot,
> >   like monitors, deadlock by erroneous usage. In this
> 
> No!  Erroneous channel usage certainly causes deadlock.  That's the only
> way deadlock occurs in occam systems.  Example:

Do you really mean this, Peter?  In occam, deadlock=STOP and thus the two
processes

CHAN OF INT a,b:	IF
PAR			  FALSE
  SEQ			    SKIP
    a! 1
    b! 1
  INT x,y:
  SEQ
    b? x
    a? y

are in every respect identical.  This actually causes real issues in model
checking---lots of IFs are potential STOPs.  

Oyvind: Yes, I'm still working hard on SPOC.  Fixing the occam output mode
has generated a flattened version of your application which provokes bugs
in occ2c's normal C mode when generating AST output.  I'm getting there.

Denis A Nicole                      WWW:   http://www.hpcc.ecs.soton.ac.uk/~dan 
High Performance Computing Centre   Email: dan@xxxxxxxxxxxxxxx                  
University of Southampton           Phone: +44 1703 592703                      
UK.                                 Fax:   +44 1703 593903