Re: Visualizing clumps

At 2011-11-16 20:26:58+0000, "Jon Harrop" writes:
> I just posted this blog article:
> 
> http://flyingfrogblog.blogspot.com/2011/11/what-is-your-garbage-collector.html
> 
> I used Mathematica to visualize the structure of the clumps (weakly
> connected components) being collected by my mark region collector whilst
> running a list-based n-queens solver. In this case, 84% of unreachable
> connected components are isolated 2-element lists and only a handful have
> interesting topologies.
> 
> I'm curious if anyone can think of a common benchmark that is likely to
> produce more interesting garbage. :-)

The arrows in your diagram appear to be pointing in the 'wrong'
direction.  For instance, I'd expect a star-shaped clump to be
produced when a central node dies which refers to several leaf nodes.
But your diagram appears to show stars with leaves pointing to the
centre.

Common benchmarks are all terrible for assessing GCs.  Run a real
program.  When I was working on MLWorks, I always used to use one
phase of our overnight build (i.e. our compiler compiling the whole
system including itself) which as I recall allocated about 10 GB.  I
would expect that to produce some much larger and more interesting
clumps.

Nick B