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Re: I'm new and wanting to help!

Hi,

On Thu, 2006-08-03 at 11:17 -0600, Tom Tromey wrote:
> Joel> I've just assumed that other VMs don't use copying collectors.
> 
> Actually I'm pretty sure that all the high-performance ones do.  But,
> I do agree, whether this is a win depends on workload, at least AIUI.
> 
> Joel> One option would be to have support for IdentityHashMaps built
> Joel> in to the GC, so that each instance is rehashed after GC.
> 
> In java the system hash code is guaranteed not to change over the
> lifetime of the object, hence the cache-it-in-the-header approach.

Robert Lougher added a compacting collector to JamVM. As far as I
understood there is a bit in the object header to indicate that the
system hash code has been taken of an object, if so, the first time the
object is moved the system hash code (address of the object at that
time) is added as an extra int to the end of the object. I CCed Robert,
I am sure he will be able to provide a better/more correct description.

Cheers,

Mark
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