Minor GCs grow longer after Full GC

[Thomas Schatzl]

Hi again,

On Thu, 2015-01-22 at 15:08 +0100, Thomas Schatzl wrote: 
> Hi Andreas,
> 
> On Thu, 2015-01-22 at 13:58 +0000, Andreas Müller wrote:
> > Hi all,
> >  
> > I have tested G1 for this application and results were worse. As I
> > understand it, management of “remembered sets” is more of a limiting
> > factor with G1 than with ParallelGC, and 
> > therefore this seems to corroborate my assumption. Is this correct?
> 
> In 7u60 there have been some improvements to remembered set management
> from code cache. This often decreases the impact of this behavior, but
> does not remove it. Young GC times will still grow over time.
> 
> Can you provide a log with -XX:+PrintGCDetails (with G1)? If you notice
> ever increasing "Ext Root Scan times", this is the exact problem.
> 
> With 8u20, G1 will not need full gc for clearing the "perm gen" any
> more. It is piggy-backed on concurrent marking.

  some correction: G1 class unloading during concurrent marking has only
been introduced with 8u40, not 8u20.

Sorry for the misinformation.

Thomas