Future of CMS

kirk at kodewerk.com kirk at kodewerk.com
Sat Jun 11 08:56:31 UTC 2016


Hi Jon,

I question that the current implementation of G1 is better than CMS. Though I do try to move my clients to G1, there are still many cases where I can get much less GC interference with CMS than I can with the G1. I can look into sending you side by side GC logs if you are interested in a visualization. At the very least I can send you contrasting Censum screenshot.

Kind regards,
Kirk Pepperdine

> On Jun 11, 2016, at 3:35 AM, Jon Masamitsu <jon.masamitsu at oracle.com> wrote:
> 
> Added hotspot-gc-dev.
> 
> On 6/10/2016 6:17 PM, Jon Masamitsu wrote:
>> Jungwoo, Ramki, Tony (and other friends of CMS),
>> 
>> I wanted to be sure you guys saw this JEP.
>> 
>> Deprecate the CMS garbage collector (UseConcMarkSweepGC).
>> http://openjdk.java.net/jeps/8142518
>> 
>> I know you do development on CMS and wanted to know if
>> had thoughts about the future of CMS.
>> 
>> At some point Oracle is going to stop supporting CMS.
>> The burden of testing and maintaining the CMS code doesn't
>> make much sense given that we think G1 is the better
>> collector.    If we deprecate CMS in jdk9, support would be dropped
>> no earlier than jdk10.
>> 
>> Have you guys talked about what you would like to do with regard
>> to continuing CMS development without Oracle's help?
>> 
>> I've been told that if CMS exists in the Oracle binaries, then
>> customers will expect it to work.  So not supporting CMS
>> means it is not in the build.
>> 
>> Jon
> 

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