RFR: bug: Timely Reducing Unused Committed Memory

Ruslan Synytsky synytskyy at jelastic.com
Thu Oct 4 12:27:10 UTC 2018


On Thu, 4 Oct 2018 at 15:06, Rodrigo Bruno <rbruno at gsd.inesc-id.pt> wrote:

> Hi Stefan,
>
>
> Stefan Johansson <stefan.johansson at oracle.com> escreveu no dia quarta,
> 3/10/2018 à(s) 21:18:
>
>>
>> We discussed this a bit further today and I'll try to summarize what we
>> currently think is the way forward and what a first version should
>> include:
>> * Periodic concurrent cycles (which after JDK-6490394 will uncommit
>> memory) are on by default, but will only trigger if no other GC has
>> occurred during the interval. The length of the interval should be
>> controlled by a flag and if set to -1, the periodic GCs will be turned
>> off. The name should probably be something other than GCFrequency, like
>> PeriodicGCInterval or so. This will be similar to what currently is
>> called CMSTriggerInterval for CMS.
>> * You can also control the periodic GCs by specifying a system average
>> load threshold, which the current avg load must be under for a periodic
>> GC to occur. This value will not be consider by default, and I think we
>> should try to come up with at more describing name than MaxLoadGC.
>> * The code checking if a periodic GC should trigger will be added to the
>> already existing G1YoungRemSetSamplingThread. This thread currently is
>> pretty idle and there are ideas around removing it, but if that is done
>> we can move the idle-checking code then.
>> * If you want the periodic GC to be a full collection, there will be a
>> flag to control this.
>>
>> Those were the key parts in our discussion, and I think Thomas plans to
>> update his webrev in a few days or so. Does this still sound like a good
>> starting point?
>>
>>
> Sounds great for me!
>
No objections on my side too.
Regards

>
> cheers,
> rodrigo
>
>
>> And also, other users having opinions are very welcome :)
>>
>> Thanks,
>> Stefan
>> >
>> > --
>> > Ruslan
>> > CEO @ Jelastic
>>
>

-- 
Ruslan
CEO @ Jelastic <https://jelastic.com/>
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