We had some serious slowness at startup before I set Xms to be the same as Xmx.
We run with an 8G heap. We have multiple collections but don’t use faceting. wunder Walter Underwood wun...@wunderwood.org http://observer.wunderwood.org/ (my blog) > On Nov 28, 2016, at 8:40 AM, Max Bridgewater <max.bridgewa...@gmail.com> > wrote: > > Thanks again Folks. I tried each suggestion and none made any difference. I > am setting up a lab for performance monitoring using App Dynamics. > Hopefully I am able to figure out something. > > On Mon, Nov 28, 2016 at 11:20 AM, Erick Erickson <erickerick...@gmail.com> > wrote: > >> bq: If you know the maximum size you ever will need, setting Xmx is good. >> >> Not quite sure what you're getting at here. I pretty much guarantee that a >> production system will eat up the default heap size, so not setting Xmx >> will >> cause OOM errors pretty soon. Or did you mean Xms? >> >> As far as setting Xms, there are differing opinions, mostly though since >> Solr >> likes memory so much there's a lot of tuning to try to determine Xmx and >> it's pretty much guaranteed that Java will need close to that amount of >> memory. >> So setting Xms=Xmx is a minor optimization if that assumption is true. >> It's arguable >> how much practical difference it makes though. >> >> Best, >> Erick >> >> On Mon, Nov 28, 2016 at 2:14 AM, Florian Gleixner <f...@redflo.de> wrote: >>> Am 28.11.2016 um 00:00 schrieb Shawn Heisey: >>>> >>>> On 11/27/2016 12:51 PM, Florian Gleixner wrote: >>>>> >>>>> On 22.11.2016 14:54, Max Bridgewater wrote: >>>>>> >>>>>> test cases were exactly the same, the machines where exactly the same >>>>>> and heap settings exactly the same (Xms24g, Xmx24g). Requests were >>>>>> sent with >>>>> >>>>> Setting heap too large is a common error. Recent Solr use the >>>>> filesystem cache, so you don't have to set heap to the size of the >>>>> index. The avalible RAM has to be able to run the OS, run the jvm and >>>>> hold most of the index data in filesystem cache. If you have 32GB RAM >>>>> and a 20GB Index, then set -Xms never higher than 10GB. I personally >>>>> would set -Xms to 4GB and omit -Xmx >>>> >>>> >>>> In my mind, the Xmx setting is much more important than Xms. Setting >>>> both to the same number avoids any need for Java to detect memory >>>> pressure before increasing the heap size, which can be helpful. >>>> >>> >>> From https://cwiki.apache.org/confluence/display/solr/JVM+Settings >>> >>> "The maximum heap size, set with -Xmx, is more critical. If the memory >> heap >>> grows to this size, object creation may begin to fail and throw >>> OutOfMemoryException. Setting this limit too low can cause spurious >> errors >>> in your application, but setting it too high can be detrimental as well." >>> >>> you are right, Xmx is more important. But setting Xms to Xmx will waste >> RAM, >>> that the OS can use to cache your index data. Setting Xmx can avoid >> problems >>> in some situations where solr can eat up your filesystem cache until the >>> next GC has been finished. >>> >>>> Without Xmx, Java is in control of the max heap size, and it may not >>>> make the correct choice. It's important to know what your max heap is, >>>> because chances are excellent that the max heap *will* be reached. Solr >>>> allocates a lot of memory to do its job. >>>> >>> >>> If you know the maximum size you ever will need, setting Xmx is good. >>> >>> >>> >>> >>
