# Lucene default FieldCache is used

**URL:** <https://discuss.elastic.co/t/lucene-default-fieldcache-is-used/4106>\
**Category:** Elasticsearch\
**Created:** [March 15, 2011, 10:56pm UTC](https://discuss.elastic.co/t/lucene-default-fieldcache-is-used/4106 "2011-03-15T22:56:36Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![zohar](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/zohar/32/3245_2.png) [@zohar](https://discuss.elastic.co/u/zohar)\
**Post date:** [March 15, 2011, 10:56pm UTC](https://discuss.elastic.co/t/lucene-default-fieldcache-is-used/4106/1 "2011-03-15T22:56:36Z")

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Hi

when running 0.15.2 we get the following warn :  
WARN [Anarchist] lucene default FieldCache is used, not enabling eager reader based cache eviction

Could not find this in the docs and would like to understand what this means.

Cheers  
Zohar

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**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\
**Post date:** [March 15, 2011, 11:06pm UTC](https://discuss.elastic.co/t/lucene-default-fieldcache-is-used/4106/2 "2011-03-15T23:06:41Z")

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elasticsearch hooks into Lucene eager eviction of caches (based on IndexReader) by overriding the FieldCache class with its own and hacking a listener mechanism. This means that without that, the cached will be cleared based on weak references in the JVM. The message you get happens because lucene jars exists in the classpath before elasticsearch, so the Lucene FieldCache class was loaded, and not the hacked on of elasticsearch.

The good news is that in upcoming Lucene 3.1 there will be a formal cache eviction listener API that elasticsearch will be able to use.  
On Wednesday, March 16, 2011 at 12:56 AM, zohar wrote:  
Hi

> when running 0.15.2 we get the following warn :  
> WARN [Anarchist] lucene default FieldCache is used, not enabling eager  
> reader based cache eviction
> 
> Could not find this in the docs and would like to understand what this  
> means.
> 
> Cheers  
> Zohar
> 
> --  
> View this message in context: [http://elasticsearch-users.115913.n3.nabble.com/lucene-default-FieldCache-is-used-tp2684277p2684277.html](http://elasticsearch-users.115913.n3.nabble.com/lucene-default-FieldCache-is-used-tp2684277p2684277.html)  
> Sent from the Elasticsearch Users mailing list archive at [Nabble.com](http://Nabble.com).

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**Author:** ![zohar](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/zohar/32/3245_2.png) [@zohar](https://discuss.elastic.co/u/zohar)\
**Post date:** [March 15, 2011, 11:09pm UTC](https://discuss.elastic.co/t/lucene-default-fieldcache-is-used/4106/3 "2011-03-15T23:09:03Z")

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I see - that makes it clear - thanks for the prompt response as ever 🙂

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 6, 2017, 4:10am UTC](https://discuss.elastic.co/t/lucene-default-fieldcache-is-used/4106/4 "2017-07-06T04:10:01Z")

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Closed on July 6, 2017, 4:10am UTC