Future of CMS
jon.masamitsu at oracle.com
Sat Jun 11 22:06:29 UTC 2016
On 6/11/2016 6:37 AM, Volker Simonis wrote:
> Hi Jon,
> I'm a little bit disappointed that you didn't think about SAP when you
> sent your initial mail ;)
Yup, I should have just addressed it to the alias so that everyone's
would have pushed it off to the side for later reading :-)
> But seriously: SAP is supporting CMS and will probably do so for quite
> a long time (simply because we do support old Java releases for a very
> long time).
> Completely removing CMS from the HotSpot code base may increase these
> support costs considerably for us.
> Do you plan to really delete the sources from the repos or do you only
> plan to disable it at build time?
I just don't know how this is going to play out. I expect that the
will want the sources to stay. In such a case Oracle would want them
that we don't build the the sources.
> I think only disable it at build time would make it easier for us and
> others to still support it in the future. But in that case we really
> have to come up with a better development model which would allow
> external developers to directly push CMS changes (much like ppc64 or
> aarch64 changes). Everything else would be a real PITA.
I think some model like ppc64/aarch64 would be a good way to go. That
would be a
nice side effect of this change. You know better than I on how to get
> Thank you and best regards,
> On Saturday, June 11, 2016, Jon Masamitsu <jon.masamitsu at oracle.com
> <mailto: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).
> 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
> 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.
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