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From "Weldon Washburn" <weldon...@gmail.com>
Subject Re: [drlvm] vote on class unloading design (was Class unloading support - tested one approach)
Date Fri, 10 Nov 2006 16:17:05 GMT
Salikh,
I read the wiki page.  Good summary.  Regarding writes to the mark bit in
vtable.  I think there was also conversation on cache line invalidate
traffic causing a problem on SMP.  That is, the mark bit of a popular class
(like maybe String?) bouncing between caches.  I recall someone suggesting a
thread-specific data struct to hold the mark bits.


On 11/10/06, Salikh Zakirov <Salikh.Zakirov@intel.com> wrote:
>
> Aleksey Ignatenko wrote:
> > Actually there is one additional 4-th approach:
> >
> > *Mark and scan based approach *wich I described in the first letter.
> Java
> > heap trace is performed by VM Core and GC is not affected at all.
> >
> > So the list is:
> > 1. vtable objects( Aleksey )
> > 2. per heap space/generation boolean marker on the classloader instance(
> > Etienne )
> > 3. class reachability marker byte in vtable (Robin )
> > 4. Mark and scan based approach.
> >
> > I agree that we need to structure all appraches somehow, like
> description
> > for every approach in wiki.
>
> I've started a wiki page http://wiki.apache.org/harmony/ClassUnloading
> to summarize all discussed approaches. I hope we will eventually come
> up with the detailed end-to-end design description.
>
> I'm going now to fill in all ideas that I can pick up from the discussion,
> but I encourage all interested parties to review and correct if I get
> something incorrectly.
>
>


-- 
Weldon Washburn
Intel Enterprise Solutions Software Division

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