Question regarding G1 option to run parallel Old generation garbage collection?

[Kirk Pepperdine]

Hi Bernd,

I would say in all of the GC logs that I've looked at (and we just created and archive of 400 exemplars) from numerous applications I would say that premature tenuring is a significant problem thus suggesting that tenuring thresholds some where north of 4 and south of 8 often are required.. along with much bigger survivor spaces than is currently defaulted. In my tuning of the Scala compiler I was able to knock more than 1 minute off of an 8 minute compile by simply adjusting survivor space size and tenuring threshold. Lets just say that this problem combined with CMS not cleaning perm has been responsible for a number of very nice vacations for my family. ;-)

Regards,
Kirk



On 2012-10-25, at 11:26 PM, "Bernd Eckenfels" <bernd-2012 at eckenfels.net> wrote:

> Am 25.10.2012, 23:11 Uhr, schrieb Vitaly Davidovich <vitalyd at gmail.com>:
> 
>> You don't want to tenure them prematurely if they ultimately
>> would die fairly soon but you can't keep them in place if you're employing a copying collector.
> 
> Actually you might want to tenure them "early": if your oldgen is collected concurrently _and_ the young collection frequency is larger than a typical transaction (which is a fairly common situation).
> 
> Therefore there is an argument for using MaxTenuring=0 (or only 1). But thats not really G1 related, I just wanted to mention it.
> 
> Bernd