G1 parallel old gen collection

[charlie hunt]

Comments below.

> On Oct 4, 2016, at 3:11 PM, Christian Thalinger <cthalinger at twitter.com> wrote:
> 
>> On Oct 4, 2016, at 9:45 AM, charlie hunt <charlie.hunt at oracle.com> wrote:
>> 
>>> Is that still the case in JDK 9?
>> 
>> Yes
> 
> What’s the answer to my second question?

It’s in the backlog (not actively being worked on).

> 
>> 
>> We need to figure out why you’re getting full GCs, and what to do to avoid them.
>> 
>> If you can share the GC logs from G1, and the command line options in use, we can probably help improve the situation for you. We will likely suggest enabling +PrintAdaptiveSizePolicy so we can see why G1 is making certain adaptive decisions.
> 
> I can certainly turn that on.  On sharing logs, I have to check if that’s possible.  Also, keep in mind this is JDK 8u.

JDK 8u is fine. G1 is tunable in JDK 8u. ;-)

Btw, knowing you’re an adventurous guy :-] … If you can get your hands on a copy of the “Java Performance Companion”, there’s several chapters in it that cover in detail G1 including how to go about tuning it  (assuming you wanna know more details, or interested in going down the DIY path).

hths,

charlie

> 
>> 
>>> On Oct 4, 2016, at 2:37 PM, Christian Thalinger <cthalinger at twitter.com> wrote:
>>> 
>>> First, I apologize if I get all the terminology wrong.  You know me… this is all a blackbox to me.
>>> 
>>> I’m currently trying to run some Twitter services with G1 and the results are encouraging but not good enough.  One issue is that full GCs take much longer than with ParallelOld (3-4x longer).
>>> 
>>> Tony said that G1’s old collection is not parallel.
>>> 
>>> Is that still the case in JDK 9?  If yes, is someone at Oracle working on parallelizing it?
>> 
>