G1 eden resizing behaviour ?

[Simone Bordet]

Hi,

On Tue, Dec 9, 2014 at 3:06 PM, Thomas Schatzl
<thomas.schatzl at oracle.com> wrote:
> This may be because the heap is already very full (around
> 100-G1ReservePercent) so it cuts down on the young gen size.
>
> G1 tries to keep G1ReservePercent of heap empty to avoid evacuation
> failure.

It's not my case: I have a 32 GiB heap with a permanent live set of
about 5-6 GiB, so I should have plenty of space even with a 15 GiB or
so eden, which is what I typically see as max eden size.

> Another reason could be that G1 thinks that the pauses caused by marking
> cut too much into the available time budget (depending on your
> settings), so it decreases the heap.

You mean by the remark, which is STW ?
Indeed I have very long remark pauses (up to 2.5s), apparently caused
by weak reference processing.

I need to investigate this issue, as the application itself does not
use them (perhaps some library ?).
There is a big difference between the references processed in the
remark phase (3 millions) and those processed during a young GC (less
than a thousand).

Am I correct assuming that those processed during remark only belong
to tenured ?

Thanks !

-- 
Simone Bordet
http://bordet.blogspot.com
---
Finally, no matter how good the architecture and design are,
to deliver bug-free software with optimal performance and reliability,
the implementation technique must be flawless.   Victoria Livschitz