JEP 141: Increase the Client VM's Default Heap Size

Jon Masamitsu jon.masamitsu at oracle.com
Tue Feb 28 08:15:21 PST 2012


Sunny,

We've talked about the fallback position of trying to reserve
less that the default (say, 1G).  Would you want it all to be done
silently?  Or would you want some warning that your
not getting the whole 1G?   Or would you want a flag
(yet another flag, ugh) that you turn on that would cause
a warning?

Jon

On 02/28/12 00:57, Sunny Chan wrote:
> Michael Bien<mbien at ...>  writes:
>
>>    On 02/22/2012 12:48 AM, mark.reinhold at ... wrote:
>>> Posted: http://openjdk.java.net/jeps/141
>>>
>>> - Mark
>>>
>> additional risks:
>>    - JVM may not be able to start
>>    - could contribute to the false impression that java requires a lot of
>> memory to run (JVMs usually don't like to give memory back to the OS
>> once its in use)
>>
>> best regards,
>> michael
>>
> The "JVM may not be able to start" risk is particularly important to think
> about.
>
> At work we uses Citrix on Windows Servers and Citrix tends to fragment the
> address space by defining DLL's base address at location which breaks up the
> 32bit address space - an example of the issue is specified here:
> http://support.citrix.com/article/CTX115868)
>
> We probably want an algorithm to try a lower default -Xmx value if there isn't a
> large continuous block available for -Xmx1G.
>


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