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From "Uwe Schindler" <...@thetaphi.de>
Subject RE: Memory question
Date Tue, 15 May 2012 17:10:30 GMT
It mmaps the files into virtual memory if it runs on a 64 bit JVM. Because
of that you see the mmapped CFS files. This is outside Java Heap and is all
*virtual* no RAM is explicitely occupied except the O/S cache.

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


> -----Original Message-----
> From: Chris Bamford [mailto:chris.bamford@talktalk.net]
> Sent: Tuesday, May 15, 2012 4:47 PM
> To: java-user@lucene.apache.org
> Subject: Memory question
> 
> Hi
> 
> Can anyone tell me what happens to the memory when Lucene opens an index?
> Is it loaded into the JVM's heap or is it mapped into virtual memory
outside of
> it?
> I am running on Linux and if I use pmap on the PID of my JVM, I can see
lots of
> entries for index cfs files.
> 
> Does this mean that indexes are mapped into non-heap memory?  If so, how
> can I monitor the space my process is using if I cache open
IndexSearchers?
> 
> The details are:
> 
> Sun 64-bit JVM on Linux.
> Lucene 3.6 running in 2.3 compatibility mode (as we are in the in the
process of
> a migration to 3.6)
> 
> Thanks,
> 
> - Chris


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