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 ****ping 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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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.
Thanks,
Vladimir
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 ****ping 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
)
Hi Vladimir,
So what you are saying is, in a future Hotspot release, we will have the
ability to specify a heap greater than 32Gb for a VM and still use the
useCompressedOops switch. The VM will use compressed oops references, while
still allowing the VM overall to address more than 32Gb of heap.
What is the timeframe of such a feature (even if it is ****ue and not precise
it is fine) are we looking at - is it coming soon (less than a year)?
Thanks for your quick response.
Atul
Vladimir Kozlov-6 wrote:
>
> 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.
>
> Thanks,
> Vladimir
>
> 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 ****ping 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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Very soon. Watch for next changes coming into hotspot (jdk7).
I don't know when it will appear in the 6 update release.
"6916623: Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb"
"6954029: Improve implicit null check generation with COOP"
The first bug is closed so you may not see it but I will open it when I am done with changes.
Vladimir
atulksh wrote:
> Hi Vladimir,
> So what you are saying is, in a future Hotspot release, we will have the
> ability to specify a heap greater than 32Gb for a VM and still use the
> useCompressedOops switch. The VM will use compressed oops references, while
> still allowing the VM overall to address more than 32Gb of heap.
>
> What is the timeframe of such a feature (even if it is ****ue and not precise
> it is fine) are we looking at - is it coming soon (less than a year)?
>
> Thanks for your quick response.
>
> Atul
>
>
> Vladimir Kozlov-6 wrote:
>> 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.
>>
>> Thanks,
>> Vladimir
>>
>> 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 ****ping 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
>>
>
)
This is great to know.
Thank you so much for you quick responses.
Atul
Vladimir Kozlov-6 wrote:
>
> Very soon. Watch for next changes coming into hotspot (jdk7).
> I don't know when it will appear in the 6 update release.
>
> "6916623: Align object to 16 bytes to use Compressed Oops with java heap
> up to 64Gb"
> "6954029: Improve implicit null check generation with COOP"
>
> The first bug is closed so you may not see it but I will open it when I am
> done with changes.
>
> Vladimir
>
> atulksh wrote:
>> Hi Vladimir,
>> So what you are saying is, in a future Hotspot release, we will have the
>> ability to specify a heap greater than 32Gb for a VM and still use the
>> useCompressedOops switch. The VM will use compressed oops references,
>> while
>> still allowing the VM overall to address more than 32Gb of heap.
>>
>> What is the timeframe of such a feature (even if it is ****ue and not
>> precise
>> it is fine) are we looking at - is it coming soon (less than a year)?
>>
>> Thanks for your quick response.
>>
>> Atul
>>
>>
>> Vladimir Kozlov-6 wrote:
>>> 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.
>>>
>>> Thanks,
>>> Vladimir
>>>
>>> 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 ****ping 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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)
Hi Vladimir,
I did not find the two bugs you mentioned in the Hotspot bug database. Are
they only accessible to you internally and not exposed to the public world?
I looked here.
http://bugs.sun.com/bugdatabase/
Thanks,
Atul
Vladimir Kozlov-6 wrote:
>
> Very soon. Watch for next changes coming into hotspot (jdk7).
> I don't know when it will appear in the 6 update release.
>
> "6916623: Align object to 16 bytes to use Compressed Oops with java heap
> up to 64Gb"
> "6954029: Improve implicit null check generation with COOP"
>
> The first bug is closed so you may not see it but I will open it when I am
> done with changes.
>
> Vladimir
>
> atulksh wrote:
>> Hi Vladimir,
>> So what you are saying is, in a future Hotspot release, we will have the
>> ability to specify a heap greater than 32Gb for a VM and still use the
>> useCompressedOops switch. The VM will use compressed oops references,
>> while
>> still allowing the VM overall to address more than 32Gb of heap.
>>
>> What is the timeframe of such a feature (even if it is ****ue and not
>> precise
>> it is fine) are we looking at - is it coming soon (less than a year)?
>>
>> Thanks for your quick response.
>>
>> Atul
>>
>>
>> Vladimir Kozlov-6 wrote:
>>> 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.
>>>
>>> Thanks,
>>> Vladimir
>>>
>>> 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 ****ping 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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)
I don't have answer on this question. I don't know why 6954029 is not exposed.
Vladimir
atulksh wrote:
> Hi Vladimir,
> I did not find the two bugs you mentioned in the Hotspot bug database. Are
> they only accessible to you internally and not exposed to the public world?
>
> I looked here.
>
> http://bugs.sun.com/bugdatabase/
>
> Thanks,
>
> Atul
>
>
> Vladimir Kozlov-6 wrote:
>> Very soon. Watch for next changes coming into hotspot (jdk7).
>> I don't know when it will appear in the 6 update release.
>>
>> "6916623: Align object to 16 bytes to use Compressed Oops with java heap
>> up to 64Gb"
>> "6954029: Improve implicit null check generation with COOP"
>>
>> The first bug is closed so you may not see it but I will open it when I am
>> done with changes.
>>
>> Vladimir
>>
>> atulksh wrote:
>>> Hi Vladimir,
>>> So what you are saying is, in a future Hotspot release, we will have the
>>> ability to specify a heap greater than 32Gb for a VM and still use the
>>> useCompressedOops switch. The VM will use compressed oops references,
>>> while
>>> still allowing the VM overall to address more than 32Gb of heap.
>>>
>>> What is the timeframe of such a feature (even if it is ****ue and not
>>> precise
>>> it is fine) are we looking at - is it coming soon (less than a year)?
>>>
>>> Thanks for your quick response.
>>>
>>> Atul
>>>
>>>
>>> Vladimir Kozlov-6 wrote:
>>>> 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.
>>>>
>>>> Thanks,
>>>> Vladimir
>>>>
>>>> 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 ****ping 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
>>
>
)
Hi,
> I did not find the two bugs you mentioned in the Hotspot bug database. Are
> they only accessible to you internally and not exposed to the public world?
>
> I looked here.
>
> http://bugs.sun.com/bugdatabase/
There've been some strange things been going on with the public bug
database, most recent bugs don't seem to be public visible.
Probably some takeover related descisions, however I hope thats not
the case ....
- Clemens
)
