Re: [Boost-users] [PBGL] Results of distributed BFS on multiple processors vs. on a single processor

Subject: Re: [Boost-users] [PBGL] Results of distributed BFS on multiple processors vs. on a single processor
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2011-04-22 10:31:20

AMDG

On 04/22/2011 05:59 AM, Cedric Laczny wrote:
> it recently came to my mind again that the distributed BFS in the PBGL seems 
> to produce different results when applied to multiple processors as to when 
> applied to a single processor (s. http://lists.boost.org/boost-
> users/2010/12/64783.php)
> If this is true, I really would like to know what the reasoning is behind this 
> and it should be noted in the documentation of course to help prevent 
> surprises as in the discussion above.
> Unfortunately, at that time, no definite answer was given and this question 
> puzzled me again now...
> Any ideas on that?
> 

Why would you expect the results to be exactly the
same?  Parallelism usually introduces a certain
amount of non-determinism.

In Christ,
Steven Watanabe