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From Apache Wiki <wikidi...@apache.org>
Subject [Solr Wiki] Trivial Update of "ShawnHeisey" by ShawnHeisey
Date Wed, 31 Dec 2014 01:24:30 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Solr Wiki" for change notification.

The "ShawnHeisey" page has been changed by ShawnHeisey:
https://wiki.apache.org/solr/ShawnHeisey?action=diff&rev1=17&rev2=18

Comment:
G1HeapRegionSize was being treated as a wiki link.  Disabled.

  "
  }}}
  
- I will talk about one further G1 tuning parameter, G1HeapRegionSize.  If the Solr index
is large, entries in the [[SolrCaching#filterCache|filterCache]] may be large enough to be
allocated as "humongous allocations" which means that they are larger than 50 percent of a
G1 heap region.  Such objects are better handled in the young generation, but if they are
categorized as humoungous, they will be allocated from the old generation.
+ I will talk about one further G1 tuning parameter, !G1HeapRegionSize.  If the Solr index
is large, entries in the [[SolrCaching#filterCache|filterCache]] may be large enough to be
allocated as "humongous allocations" which means that they are larger than 50 percent of a
G1 heap region.  Such objects are better handled in the young generation, but if they are
categorized as humoungous, they will be allocated from the old generation.
  
  In terms of bytes, the size of each filterCache entry can be determined by taking the maxDoc
value from the Solr core and dividing it by 8.  For a 16 million document index, the cache
entries will each be about 2MB in size.  For that index size, you would need to use -XX:G1HeapRegionSize=8m,
so that those large objects are significantly smaller than 50 percent of the region size,
and therefore are not categorized as humongous.  See "Humongous Allocations" section on this
[[http://www.infoq.com/articles/tuning-tips-G1-GC|blog entry]] for more information.
  

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