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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject Re: [drlvm][gc] IdentityHashCode implementation on magics
Date Thu, 15 May 2008 23:42:51 GMT
Aleksey, "attached hashcode" works together with "buffered hashcode".
"Buffered hashcode" is created in compacting GC (in other words, in
major collection). So if normally there is few major collections,
there will be very few buffered hashcodes created. In minor
collections, it uses the attached hashcode.


On Fri, May 16, 2008 at 5:06 AM, Aleksey Shipilev
<aleksey.shipilev@gmail.com> wrote:
> Hi, Xiao Feng, GC gurus,
> I'm back to IdentityHashCode implementation on magics [1]. I had
> managed to inline the helper for System.identityHashCode(), but
> unfortunately I had stuck with buffered hashcode scheme. Basically,
> there is no support for buffered hashcodes in GCHelper and I doubt it
> could be implemented there as we need to traverse native data
> structure on hashcode lookup. Not saying about performance when there
> are many hashcodes in the run, I have a suspicion there is the problem
> too.
> So I wonder whether is it possible to turn on "attached hashcode"
> instead of "buffered hashcode" somehow to see the performance impact?
> I searched through sources and it's still unclear for me.
> Thanks,
> Aleksey.
> [1] https://issues.apache.org/jira/browse/HARMONY-5713


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