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 > >
