UseCompressedOops switch with more than 32gb heaps...

Vladimir Kozlov vladimir.kozlov at
Thu May 27 18:03:00 UTC 2010

I am currently working on this. You have to increase java objects alignment
(from current 8 bytes) to be able to use compressed pointers (which are 32 bit)
which large heaps.


atulksh wrote:
> Hi,
> We are currently running our application servers with 26Gb of heap and have
> the UseCompressedOops enabled for memory savings. We are intending to boost
> the memory on our servers more, in which event, we would be bumping the heap
> above 32Gb. I know that the UseCompressedOops switch works only if you have
> a heap of 32Gb or less.
> Is there anything in the Hotspot VM roadmap where there may be support of
> heaps larger than 32Gb, and still using the UseCompressedOops switch for
> memory optimization (32 bit object pointers within the heap)? Or is this
> question irrelevent - meaning there is no possibility to have such a support
> on the 64 bit machines?
> Thank you for your response in advance.
> Atul

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