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From "Uwe Schindler" <...@thetaphi.de>
Subject RE: Lucene Version Upgrade (3->4) and Java JVM Versions(6->8)
Date Tue, 27 Jan 2015 20:02:56 GMT
Hi.,

About G1GC. We consistently see problems when running the Lucene Testsuite with G1GC enabled.
The people from Elasticsearch concluded:

"There is a newer GC called the Garbage First GC (G1GC). This newer GC is designed to minimize
pausing even more than CMS, and operate on large heaps. It works by dividing the heap into
regions and predicting which regions contain the most reclaimable space. By collecting those
regions first (garbage first), it can minimize pauses and operate on very large heaps.

Sounds great! Unfortunately, G1GC is still new, and fresh bugs are found routinely. These
bugs are usually of the segfault variety, and will cause hard crashes. The Lucene test suite
is brutal on GC algorithms, and it seems that G1GC hasn’t had the kinks worked out yet.

We would like to recommend G1GC someday, but for now, it is simply not stable enough to meet
the demands of Elasticsearch and Lucene."
(http://www.elasticsearch.org/guide/en/elasticsearch/guide/current/_don_8217_t_touch_these_settings.html)

In fact, the problems with G1GC can sometimes lead to index corruption, and are hard to reproduce.
So better don't use...

Uwe

-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe@thetaphi.de


> -----Original Message-----
> From: McKinley, James T [mailto:james.mckinley@cengage.com]
> Sent: Tuesday, January 27, 2015 8:58 PM
> To: java-user@lucene.apache.org
> Subject: RE: Lucene Version Upgrade (3->4) and Java JVM Versions(6->8)
> 
> Why do you say not to use G1GC?  We are using Java 7 & G1GC with Lucene
> 4.8.1 in production.  Thanks.
> 
> Jim
> ________________________________________
> From: Uwe Schindler [uwe@thetaphi.de]
> Sent: Tuesday, January 27, 2015 2:49 PM
> To: java-user@lucene.apache.org; 'kiwi clive'
> Subject: RE: Lucene Version Upgrade (3->4) and Java JVM Versions(6->8)
> 
> Java 8 update 20 or later is also fine. At current time, always use latest update
> release and you are be fine with Java 7 and Java 8. Don't use older releases
> and don't use G1 Garbage Collector.
> 
> -----
> Uwe Schindler
> H.-H.-Meier-Allee 63, D-28213 Bremen
> http://www.thetaphi.de
> eMail: uwe@thetaphi.de
> 
> 
> > -----Original Message-----
> > From: kiwi clive [mailto:kiwi_clive@yahoo.com.INVALID]
> > Sent: Tuesday, January 27, 2015 8:03 PM
> > To: java-user@lucene.apache.org
> > Subject: Re: Lucene Version Upgrade (3->4) and Java JVM Versions(6->8)
> >
> > Hi Hoss,
> > Many thanks for the information. This looks very encouraging as the
> > Java7 bug I remember  was fixed and as far as I know, we should not be
> > affected by the others.
> > I'll put a few tests together and put my toe in the water :-) Clive
> >
> >       From: Chris Hostetter <hossman_lucene@fucit.org>
> >  To: "java-user@lucene.apache.org" <java-user@lucene.apache.org>; kiwi
> > clive <kiwi_clive@yahoo.com>
> >  Sent: Tuesday, January 27, 2015 4:01 PM
> >  Subject: Re: Lucene Version Upgrade (3->4) and Java JVM
> > Versions(6->8)
> >
> >
> >
> >
> > : I seem to remember reading that certain versions of lucene were
> > : incompatible with some java versions although I cannot find anything
> > to
> > : verify this. As we have tens of thousands of large indexes,
> > backwards
> > : compatibility without the need to reindex on an upgrade is of prime
> > : importance to us.
> >
> > All known JVM bugs affecting Lucene are listed here...
> >
> > https://wiki.apache.org/lucene-java/JavaBugs
> >
> >
> > -Hoss
> > http://www.lucidworks.com/
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> > For additional commands, e-mail: java-user-help@lucene.apache.org
> >
> >
> >
> >
> 
> 
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> 
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