[gambit-list] Termite problems

Nicholas Walton nwalton at mac.com
Tue Feb 19 15:38:08 EST 2008


Hi,

I've just started working with Termite to distribute the processing  
for a large data mining system over a multi core CPU and I seem to be  
hitting a few problems for which any advice is welcome.

Small scale examples seem to work well but once I scale up I hit  
problems. I'm running on a 1Gig Mac using OS X 10.4 with  the latest  
distribution of Gambit and the current tarball from the Termite site  
together with the slib library.

At first I built a two process client server example but it hung. The  
problem turned out to be the array.scm file in the slib distribution  
redefining the equal? procedure. Once the redefinition was removed all  
worked well. So long as I used tags and not pids to identify one  
remote process to another. The pid returned by remote-spawn is not the  
same as that returned by the process calling (self).

I then moved on to trying a parallel version of map, akin to that  
given at http://theschemeway.blogspot.com/2007/06/parallel-map-with-termite.html 
. That worked fine for small simple examples but when I threw in a  
larger example, evaluating forty instances of a k-means cluster  
procedure in parallel in one process, it consistently dumps core but  
not in any predictable manner. All forty threads kick off fine but  
while some succeed others fail catastrophically  and at no particular  
point resulting in Gambit dumping core. I've run the code using map  
and all was well, and the code has nothing in it which seems likely to  
cause the problem. I've run the code both compiled and fully  
interpreted and the behavior is the same.

First is there any changes to the Gambit build which might help  
identifying where the fault is occurring? Secondly  are there known  
problems with Termite especially when spawning moderately large  
processes.?

Many Thanks

Nick Walton




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