Re: Visualizing clumps

Nick wrote:
> 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.

These are immutable singly-linked lists with sharing. So several different
list nodes (cons cells) can refer to the same tail but each list node can
only refer to zero or one other lists. For example, a "star" with three legs
might signify the deaths of the three different lists [2;1], [3;1] and [4;
1] that all shared the same physical tail list [1].

Until I zoomed in, I hadn't noticed that most of the 3-vertex components are
of the form x->y<-z rather than x->y->z, which is interesting...

> Common benchmarks are all terrible for assessing GCs.  Run a real program.

Yes, I thought that might be the case. :-)

> 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.

I'll do so if I can find the time but my objective was more to inspire than
to research thoroughly. Hopefully someone else is in a better position than
I to generate data from real programs.

Cheers,
Jon.