G1 "to-space exhausted" causes used heap space to increase?

[Yu Zhang]

I am starting a FAQ page, I added this question 
https://blogs.oracle.com/g1gc/


      9. What is the recommended way to limit Eden size for g1?

  The recommended way is to set  -XX:MaxGCPauseMillis.  G1 will adjust 
YoungGen size trying to meet the pause goal.  The Young gen size is 
between 5 to 60 percent of the heap size.  To control it further, you 
can use Experimental flags:

-XX:+UnlockExperimentalVMOpt -XX:G1NewSizePercent=<5> 
-XX:G1MaxNewSizePercent=<60>.

  G1 will pick up other settings, such as NewRatio, NewSize, MaxNewSize, 
-Xmn

-Xmn: the same as NewSize=MaxNewSize

only -XX:NewSize is set, the young gen size is between specified NewSize 
and  G1MaxNewSizePercent

only -XX:MaxNewSize is set, the young gen size is between 
specified G1NewSizePercent and MaxNewSize.

Both  -XX:NewSize and  -XX:MaxNewSize are used, young gen will be 
between those 2 sizes.  But when heap size change, the young gen size 
will not change accordingly.

If  -XX:NewRatio is used, the Young Gen size is heap size * newRatio. 
  NewRatio is ignored if it is used with NewSize and MaxNewSize.


Thanks,
Jenny

On 3/2/2015 10:15 AM, Simone Bordet wrote:
> Hi,
>
> On Mon, Mar 2, 2015 at 6:44 PM, Christopher Berner
> <christopherberner at gmail.com> wrote:
>> Hello,
>>
>> I work on the Presto project (https://github.com/facebook/presto) and am
>> trying to understand the behavior of G1. We run a 45GB heap on the worker
>> machines with "-XX:G1HeapRegionSize=32M", and it works smoothly,
> Just out of curiosity, you seem to have IHOP=45% and an eden that is
> 55% of the heap (25 GiB out of 45 GiB).
> Is there any reason why you keep IHOP this low or you're just running
> with defaults ?
>
> To the hotspot gc experts, is there any way to limit the Eden size
> without impacting on the ergonomics ?
> Does -XX:MaxNewSize impact ergonomics ?
>

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