[Vm-dev] An idea about better finalization support

Eliot Miranda eliot.miranda at gmail.com
Wed Apr 22 23:01:21 UTC 2009

On Wed, Apr 22, 2009 at 3:50 PM, John M McIntosh <
johnmci at smalltalkconsulting.com> wrote:

> Well there was the Ephemerons stuff you can add too
> http://map.squeak.org/package/fe2a35f5-3f97-431e-8596-58e810aa3c72
> ian had a version he pushed out a couple of years, back which was retracted
> because it
> caused VM crashs, but later was proven to be an off by 1 C/slang coding
> error.
> But no-one I think had the courage to inflict back onto the community.
> Er so how would compatibilty work with this new way given an image which
> may or may not include image side companion code.

We'd still need to support weak arrays.  But Ephemerons allow instance-based
finalization, so they're a big step up on the postmortem finalization
offered by weak arrays.

The current state of Cog is that with simple code generation and
machine-code floating-point primitives the nbody benchmark form the computer
language shootout is spending 40% of entire execution time in the
incremental GC.  So my next target will be te new two-word object header and
a scavenger rather than a deferred code generator.  I'm thinking of looking
closely at the V8 GC (Lars Bak's presentation at Microsoft last
and I could probably add ephemerons to that in a second rev.

> --
> ===========================================================================
> John M. McIntosh <johnmci at smalltalkconsulting.com>
> Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
> ===========================================================================
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