G1 parallel old gen collection
yu.zhang at oracle.com
Tue Oct 4 20:11:43 UTC 2016
On 10/4/2016 1:01 PM, Vitaly Davidovich wrote:
> On Tue, Oct 4, 2016 at 3:37 PM, Christian Thalinger
> <cthalinger at twitter.com <mailto: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).
> As Charlie says, you really want to avoid Full GCs in G1 - they're
> super slow, and are really a last resort. They're not intended to be
> part of normal operation.
> I've seen them occur when concurrent marking is either started too
> late or concurrent marking loses the race with java mutators. There
> are several ways to mitigate this, but as Charlie said, you'll need to
> provide more info Chris.
Also with jdk9, the ihop is dynamic adjusted to avoid the 'started too
> 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?
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