Hi Steve, Fluctuation is OK. 100% utilization for more than a moment is not :)
Not sure what tool(s) you use for monitoring your Solr servers, but look under "JVM Pool Utilization" in SPM if you're using SPM. Or this live demo of a Solr system: * click on https://apps.sematext.com/demo to get into the demo account * look at "JVM Pool Utilization" on https://apps.sematext.com/spm-reports/mainPage.do?selectedApplication=1704&r=poolReportPage×tamp=1449865787801&stickyFiltersOff=false And on that JVM Pool Size chart on top of the page you will see giant saw pattern.... which is a healthy sign :) HTH Otis -- Monitoring - Log Management - Alerting - Anomaly Detection Solr & Elasticsearch Consulting Support Training - http://sematext.com/ On Wed, Dec 9, 2015 at 9:56 AM, Steven White <swhite4...@gmail.com> wrote: > Thanks Erick!! Your summary and the blog by Uwe (thank you too Uwe) are > very helpful. > > A follow up question. I also noticed the "JVM-Memory" report off Solr's > home page is fluctuating. I expect some fluctuation, but it kinda worries > me when it fluctuates up / down in a range of 4 GB and maybe more. I.e.: > at times it is at 5 GB and other times it is at 10 GB (this is while I'm > running my search tests). What does such high fluctuation means? > > If it helps, Solr's "JVM-Memory" report states 2.5 GB usage when Solr is > first started and before I run any search on it. I'm taking this as my > base startup memory usage. > > Steve > > On Tue, Dec 8, 2015 at 3:17 PM, Erick Erickson <erickerick...@gmail.com> > wrote: > > > You're doing nothing wrong, that particular bit of advice has > > always needed a bit of explanation. > > > > Solr (well, actually Lucene) uses MMapDirectory for much of > > the index structure which uses the OS memory rather than > > the JVM heap. See Uwe's excellent: > > > > http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on-64bit.html > > > > Plus, the size on disk includes the stored data, which is in the *.fdt > > files in data/index. Very little of the stored data is kept in the JVM > > so that's another reason your Java heap may be smaller than > > your raw index size on disk. > > > > The advice about fitting your entire index into memory really has > > the following caveats (at least). > > 1> "memory" includes the OS memory available to the process > > 2> The size of the index on disk is misleading, the *.fdt files > > should be subtracted in order to get a truer picture. > > 3> Both Solr and Lucene create structures in the Java JVM > > that are _not_ reflected in the size on disk. > > > > <1> and <2> mean the JVM memory necessary is smaller > > than the size on disk. > > > > <3> means the JVM memory will be larger than. > > > > So you're doing the right thing, testing and seeing what you > > _really_ need. I'd pretty much take your test, add some > > padding and consider it good. You're _not_ doing the > > really bad thing of using the same query over and over > > again and hoping <G>. > > > > Best, > > Erick > > > > > > On Tue, Dec 8, 2015 at 11:54 AM, Steven White <swhite4...@gmail.com> > > wrote: > > > Hi folks, > > > > > > My index size on disk (optimized) is 20 GB (single core, single index). > > I > > > have a system with 64 GB of RAM. I start Solr with 24 GB of RAM. > > > > > > I have run load tests (up to 100 concurrent users) for hours where each > > > user issuing unique searches (the same search is never executed again > for > > > at least 30 minute since it was last executed). In all tests I run, > > Solr's > > > JVM memory never goes over 10 GB (monitoring http://localhost:8983/). > > > > > > I read over and over, for optimal performance, Solr should be given > > enough > > > RAM to hold the index in memory. Well, I have done that and some but > > yet I > > > don't see Solr using up that whole RAM. What am I doing wrong? Is my > > test > > > at fault? I doubled the test load (number of users) and didn't see > much > > of > > > a difference with RAM usage but yet my search performance went down > > (takes > > > about 40% longer now). I run my tests again but this time with only 12 > > GB > > > of RAM given to Solr. Test result didn't differ much from the 24 GB > run > > > and Solr never used more than 10 GB of RAM. > > > > > > Can someone help me understand this? I don't want to give Solr RAM > that > > it > > > won't use. > > > > > > PS: This is simply search tests, there is no update to the index at > all. > > > > > > Thanks in advanced. > > > > > > Steve > > >
