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List:       openjdk-hotspot-gc-dev
Subject:    no-administration heap?
From:       walters () verbum ! org (Colin Walters)
Date:       2008-02-28 23:09:05
Message-ID: faa16b610802281509m7b4cb9a2o43757feffea41390 () mail ! gmail ! com
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On Thu, Feb 28, 2008 at 5:46 PM, Peter B. Kessler <Peter.Kessler at sun.com> wrote:
>
>  Nothing is "too invasive"!  We have a sketch of a "chunked heap";
>  it's just a lot of work.  Things like the card table that used to
>  be indexed by offsets in the heap become part of each heap chunk
>  and are indexed by an offset in the chunk.  A lot of the underlying
>  data structures have to be rewritten, but that's why they call it
>  software.  We would *love* to have that kind of heap.

Great to hear there's work in this area!  I'll be keeping an eye on
the progress; I'm planning to convert a CPython application to
OpenJDK+Jython, and this issue is one thing that would be nice to have
solved.

>  Then there are "details" like that once you chunk the heap you
>  limit the maximum size of an object.  I was thinking that 64MB
>  chunks might be one possibility in that they would let you have
>  (somewhat less than) a 64MB array, which is the largest you can
>  have now on the client unless you use a larger -Xmx.

Large byte arrays might be interesting to support, but otherwise a
64MB limit sounds reasonable.


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