Oh, blimey, have Oracle gone with Ubuntu-style numbering now? :) On 7 November 2017 at 08:27, Markus Jelsma <markus.jel...@openindex.io> wrote:
> Shawn, > > There won't be a Java 10, we'll get Java 18.3 instead. After 9 it is a > guess when CMS and friends are gone. > > Regards, > Markus > > > > -----Original message----- > > From:Shawn Heisey <apa...@elyograg.org> > > Sent: Tuesday 7th November 2017 0:24 > > To: solr-user@lucene.apache.org > > Subject: Re: Java 9 > > > > On 11/6/2017 3:07 PM, Petersen, Robert (Contr) wrote: > > > Anyone else been noticing this this msg when starting up solr with > java 9? (This is just an FYI and not a real question) > > > > > > Java HotSpot(TM) 64-Bit Server VM warning: Option UseConcMarkSweepGC > was deprecated in version 9.0 and will likely be removed in a future > release. > > > Java HotSpot(TM) 64-Bit Server VM warning: Option UseParNewGC was > deprecated in version 9.0 and will likely be removed in a future release. > > > > I have not tried Java 9 yet. > > > > Looks like G1 is now the default garbage collector. I did not know that > > they were deprecating CMS and ParNew ... that's a little surprising. > > Solr's default garbage collection tuning uses those two collectors. It > > is likely that those choices will be available in all versions of Java > > 9. It would be very uncharacteristic for Oracle to take action on > > removing them until version 10, possibly later. > > > > If it were solely up to me, I would adjust Solr's startup script to use > > the G1 collector by default, eliminating the warnings you're seeing. > > It's not just up to me though. Lucene documentation says to NEVER use > > the G1 collector because they believe it to be unpredictable and have > > the potential to cause problems. I personally have never had any issues > > with it. There is *one* Lucene issue mentioning problems with G1GC, and > > that issue is *specific* to the 32-bit JVM, which is not recommended > > because of the limited amount of memory it can use. > > > > My experiments with GC tuning show the G1 collector (now default in Java > > 9) to have very good characteristics with Solr. I have a personal page > > on the Solr wiki that covers those experiments. > > > > https://wiki.apache.org/solr/ShawnHeisey > > > > Thanks, > > Shawn > > > > >
