Performance degradation with two collection on same sole instance

[SolrUser1543 <os...@gmail.com>]

we have a large solr cloud , with one collection and no replicas .
Each machine has one solr core .
Recently we decided to add a new collection , based on same schema , so now
each solr instance has two cores .
First collection has very big index , but the new one has only several
hundreds of documents.

Day after we did it , we experienced very strong performance degradation,
like long query times and server unavailability.

JVM was configured to 20GB heap , and we did not changed it during addition
of a new collection.

The question is , how Solr manages its resources when it has more than one
core ? Does it need twice memory ? Or this degradation might be a
coincidence ?    



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Re: Performance degradation with two collection on same sole instance

[SolrUser1543 <os...@gmail.com>]

we have 100 gb ram on each machine . 20 gb - for heap . index size of big
collection is 130 gb . the new second collection has only few documents ,
only few MB  .

When we disabled new cores , performance has improved . 

Both collection using same solr.config , so they have same filter
configurations .

But the second collection very small , only few documents , so cache can not
consume a memory .





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Re: Performance degradation with two collection on same sole instance

[Jan Høydahl <ja...@cominvent.com>]

You say you configure 20Gb heap. What is your total physical RAM on the host?
What are your cache sizes for the two collections?
If you have too high cache settings you may eat too much memory..

--
Jan Høydahl, search solution architect
Cominvent AS - www.cominvent.com

> 27. okt. 2015 kl. 20.12 skrev SolrUser1543 <os...@gmail.com>:
> 
> we have a large solr cloud , with one collection and no replicas .
> Each machine has one solr core .
> Recently we decided to add a new collection , based on same schema , so now
> each solr instance has two cores .
> First collection has very big index , but the new one has only several
> hundreds of documents.
> 
> Day after we did it , we experienced very strong performance degradation,
> like long query times and server unavailability.
> 
> JVM was configured to 20GB heap , and we did not changed it during addition
> of a new collection.
> 
> The question is , how Solr manages its resources when it has more than one
> core ? Does it need twice memory ? Or this degradation might be a
> coincidence ?    
> 
> 
> 
> --
> View this message in context: http://lucene.472066.n3.nabble.com/Performance-degradation-with-two-collection-on-same-sole-instance-tp4236774.html
> Sent from the Solr - User mailing list archive at Nabble.com.

Re: Performance degradation with two collection on same sole instance

[Toke Eskildsen <te...@statsbiblioteket.dk>]

On Tue, 2015-10-27 at 12:12 -0700, SolrUser1543 wrote:
> The question is , how Solr manages its resources when it has more than one
> core ? Does it need twice memory ? Or this degradation might be a
> coincidence ?    

There is an overhead for each core, but not much. You should not notice
any performance degradation from the secondary tiny core. An easy way to
check is to remove the extra core and see if that returns performance
back to the previous level. Preferably you should do this without
restarting the Solr instance as doing so affects performance temporarily
until it stabilizes.

- Toke Eskildsen, State and University Library, Denmark