[gclist] Re: Name that hypothesis

Henry G. Baker hbaker@netcom.com
Wed, 4 Dec 1996 11:59:04 -0800 (PST)

> On Dec 4, 10:54am, Charles Fiterman wrote:
> > Subject: Re: [gclist] Re: Name that hypothesis
> > > || What is the name of the following hypothesis?
> > > ||
> > > || 	"Most references in a system point backwards in time, i.e. from
> > > || 	 younger objects to older objects."
> > >
> > >We tested that hypothesis.  It is incorrect.
> > >
> > >Specifically, here is how some well-known C programs behave:
> >
> > I see systematic sampling error here. The programs are all in C.
> >
> The problem is that the real world has committed a systematic sampling error:
>  All the real programs most of us use are written in C (probably with some
> amount of C++ of various flavors thrown in, depending on the platform).


> Particular languages seem to encourage very specific programming styles, making
> it hard to generalize to anything else.  For example, Manuel Serrano concluded
> that ML programs (perhaps especially ML benchmarks), benefit much more from
> generational collection than even Scheme programs.
> Hans-Juergen Boehm
> boehm@mti.sgi.com

I agree with Hans re programming styles.  I also forgot to mention
some work from the _lazy_ functional programming community, whose
results are much more like those of the logic programming community
than those of the strict functional programming community -- e.g., ML.
The reason is that the lazy values get updated _after_ the links to
them are created, and this screws up generational GC's pretty badly.
I seem to recall several papers in the past several years from FPCA
and some of the GC conferences that ran into this problem.  I also
seem to recall that the problem can be ameliorated, but I don't recall
off the top of my head how this was done.

Henry Baker
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