[prev in list] [next in list] [prev in thread] [next in thread] 

List:       solr-user
Subject:    Re: Is Solr cache cleared when I restart Solr?
From:       Zheng Lin Edwin Yeo <edwinyeozl () gmail ! com>
Date:       2016-01-30 14:26:36
Message-ID: CAF2DzVVeR2iM1viHTZs90TqPPP4y84oiYka7gOzTr9RcDrJUjg () mail ! gmail ! com
[Download RAW message or body]


I did change the JVM heap size from 16GB to 24GB. Will that make a
difference?

Regards,
Edwin

On 28 January 2016 at 22:10, Alessandro Benedetti <abenedetti@apache.org>
wrote:

> As already specified you need to distinguish between Solr Cache and OS
> Memory mapped files.
> What you should clearly notice in your situation is an increase of space
> for the OS Memory mapped files.
> Which means faster access to index segments ( almost all the different data
> structures are memory mapped ).
>
> Related the internal Solr Cache, if you haven't changed the java memory
> properties, I would expect not that much difference.
> If you were on a virtual machine sharing physical memory with other virtual
> instances, you could find benefits on the other hand.
>
> Cheers
>
>
> On 28 January 2016 at 05:44, Zheng Lin Edwin Yeo <edwinyeozl@gmail.com>
> wrote:
>
> > Thanks Erick and Shawn for your reply.
> >
> > We have recently upgraded the server RAM from 64MB to 192MB, and I
> noticed
> > that this caching occurs after we upgraded the RAM. Previously, the cache
> > may not even be preserved in the same Solr session.
> > So is it true that the upgrading of the server RAM creates enough spare
> > memory for good caching?
> >
> > Regards,
> > Edwin
> >
> >
> > On 28 January 2016 at 12:27, Shawn Heisey <apache@elyograg.org> wrote:
> >
> > > On 1/27/2016 8:11 PM, Zheng Lin Edwin Yeo wrote:
> > > > I would like to find out, is the cache in the Solr cleared when I
> shut
> > > down
> > > > the Solr instant and restart it?
> > > >
> > > > I am suspecting that the cache is not entirely cleared, because when
> I
> > > try
> > > > to do a search on the same query as I did before the search, it still
> > > has a
> > > > return QTime that is much faster than the initial search. However,
> > when I
> > > > do a search on a new query, the return QTime is the original speed.
> > > >
> > > > I am using Solr 5.4.0, and this is my setting for the
> queryResultCache.
> > > >
> > > >     <queryResultCache class="solr.LRUCache"
> > > >                      size="1024"
> > > >                      initialSize="512"
> > > >                      autowarmCount="0"/>
> > >
> > > The Solr caches are maintained in the Java heap, which is lost when
> Java
> > > stops.
> > >
> > > Although the Solr caches are not preserved across a restart, the
> > > operating system does cache actual index data in main memory, so when
> > > Solr asks for the same index data off of the disk again, it is pulled
> > > directly from RAM, which is a LOT faster than the disk.  In order to
> > > deliver good performance, Solr is extremely reliant on this built-in
> > > feature of all modern operating systems, so there must be enough spare
> > > memory for good caching.
> > >
> > > Here are a couple of pages with some more detail:
> > >
> > > https://wiki.apache.org/solr/SolrPerformanceProblems
> > > https://en.wikipedia.org/wiki/Page_cache
> > >
> > > Thanks,
> > > Shawn
> > >
> > >
> >
>
>
>
> --
> --------------------------
>
> Benedetti Alessandro
> Visiting card : http://about.me/alessandro_benedetti
>
> "Tyger, tyger burning bright
> In the forests of the night,
> What immortal hand or eye
> Could frame thy fearful symmetry?"
>
> William Blake - Songs of Experience -1794 England
>


[prev in list] [next in list] [prev in thread] [next in thread]