We are using Sitecore 8.0 Update 2 and Solr 4.10.3.

Today we had a website crash because Solr went down and our listing pages and search related components weren't working. The issue turned out to be that Solr was using 99% of the RAM. The Solr server has 8 GBs of RAM and JVM has the same allocated to it. It has never been a problem and for the last 2 years. The average RAM/JVM usage was about 30-40% of the total. But it spiked in the last couple of days and only a server restart helped it come back up.

After restarting the server the JVM is growing by a 100 or so MB every few seconds and seems to peak at about 3-4 GB but then it goes down to below 1 GB right away. The CM is the only server that does any indexing and the traffic on there is rather below average since Friday. The CDs are also not showing any high traffic rather average traffic.

Has anyone come across this scenario before? Do we need to add more RAM and increase JVM on the Solr server?

1 Answer 1


Sitecore recommends a minimum of 16GB of RAM when setting up the infrastructure. Please see the Installation Guide from Sitecore here.

The issue that you may have experienced also is maybe due to the fact that there were an increase in the number of queries to the Solr server.

Maybe try also to see if you have any query causing performance issue.


There are different profiling tools that you can used. Paid and free versions.

  1. DynaTrace - Paid
  2. YourKit - Has trial
  3. Stackift Prefix - Both free and Paid version
  4. SPM - This service will expose request rates, latency, all Solr cache info, JVM memory, GC, CPU, load, disk and network IO, etc. It has a free trial
  • I went through that page and we have decided to up the RAM on the SOLR server. So that should be coming. Do you recommend any tools to diagnose query performance issues?
    – Gabbar
    Mar 20, 2017 at 20:33
  • @Gabbar, please see update section from answer Mar 20, 2017 at 20:43
  • This may be too basic, but Solr logs should have each query performed by the server. Something like blog.alpha-solutions.us/2017/01/… gives an example of what you can find in those logs.
    – G Killian
    Mar 20, 2017 at 23:57

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