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From "Fuad Efendi" <>
Subject RE: Solr and Garbage Collection
Date Tue, 06 Oct 2009 20:19:50 GMT
Master-Slave replica: new caches will be warmed&prepopulated _before_ making
new IndexReader available for _new_ requests and _before_ discarding old one
- it means that theoretical sizing for FieldCache (which is defined by
number of docs in an index and cardinality of a field) should be doubled...
of course we need to play with GC options too for performance tuning

> > I read pretty much all posts on this thread (before and after this one).
> Looks
> > like the main suggestion from you and others is to keep max heap size
> (-Xmx)
> > as small as possible (as long as you don't see OOM exception).
> I suggested absolute opposite; please note also that "as small as
> does not have any meaning in multiuser environment of Tomcat. It depends
> query types (10 documents per request? OR, may be 10000???) AND it depends
> on average server loading (one concurrent request? Or, may be 200 threads
> trying to deal with 2000 concurrent requests?) AND it depends on whether
> is Master (used for updates - parses tons of docs in a single file???) -
> it depends on unpredictable memory fragmentation - it all depends on use
> case too(!!!), additionally to schema / index size.
> Please note also, such staff depends on JVM vendor too: what if it
> precompiles everything into CPU native code (including memory dealloc
> each call)? Some do!
> -Fuad
> ...but 'core' constantly disagrees with me :)

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