RFR: 8186248 - Allow more flexibility in selecting Heap % of available RAM

David Holmes david.holmes at oracle.com
Wed Aug 23 02:26:03 UTC 2017

Hi Bob,

On 23/08/2017 4:22 AM, Bob Vandette wrote:
> Please review the updated webrev which adds new VM flags to allow for the manual
> selection of Heap size based on a percentage of total available memory.
> This version deprecates the existing fractional options and allows the new % based flags
> to override.
> http://cr.openjdk.java.net/~bobv/8186248/webrev.01/ <http://cr.openjdk.java.net/~bobv/8186248/webrev.01/>

Deprecation of flags is done by adding them to the table of 
deprecated/obsoleted/expired flags.

I would expect this change to do a conversion from the existing flags to 
the new flags, and then all remaining code should only refer to the new 
flags i.e. the deprecated flags should only exist in the globals.hpp 
file, the deprecation table, and the place where their values are 
(potentially) assigned to the new flags.


> Bob.
>> On Aug 17, 2017, at 12:36 AM, David Holmes <David.Holmes at oracle.com> wrote:
>> On 17/08/2017 1:29 PM, Bob Vandette wrote:
>>> I saw that but wasn't sure it needed the added flexibility since its probably ok that initial sizes are 50% or less.
>> I'd go for consistency.
>> Also now you will need to guard against values < 1, I think.
>> There may be an option checking test that will need updating as well.
>> Cheers,
>> David
>>> Bob.
>>>> On Aug 16, 2017, at 5:04 PM, David Holmes <david.holmes at oracle.com> wrote:
>>>> Hi Bob,
>>>>> On 17/08/2017 3:32 AM, Bob Vandette wrote:
>>>>> Please review this simple two line fix which allows more flexibility in selecting the % of system RAM
>>>>> to be used by the Heap.  This just changes two int variables to doubles.
>>>>> RFE:
>>>>> https://bugs.openjdk.java.net/browse/JDK-8186248 <https://bugs.openjdk.java.net/browse/JDK-8186248>
>>>>> Webrev:
>>>>> http://cr.openjdk.java.net/~bobv/8186248 <http://cr.openjdk.java.net/~bobv/8186248>
>>>> Wouldn't you also want/need to change the type of InitialRAMFraction?
>>>> Note: jdk10/hs is currently closed to changes as we prepare to push up to jdk10/jdk10.
>>>> Thanks,
>>>> David
>>>>> Bob.

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