I used GC in different situations and tried back and forth. Yes, it reduces the used heap memory, but not by 5GB. Even so that GC from jconsole (or jvisualvm) is "Full GC".
But while you bring GC into this, there is another interesting thing. - I have one slave running for a week which ends up around 18 to 20GB of heap memory. - the slave goes offline for replication (no user queries on this slave) - the slave gets replicated and starts a new searcher - the heap memory of the slave is still around 11 to 12GB - then I initiate a Full GC from jconsole which brings it down to about 8GB - then I call optimize (on a optimized index) and it then drops to 6.5GB like a fresh started system I have already looked through Uwe's blog but he says "...As a rule of thumb: Don’t use more than 1/4 of your physical memory as heap space for Java running Lucene/Solr,..." That would be on my server 8GB for JVM heap, can't believe that the system will run for longer than 10 minutes with 8GB heap. Next tests will be with all autowarm off. This is for the FullGC/optimize problem after replication. But for the 5GB jump I have no idea. May be changing the cache sizes? Regards Bernd Am 18.09.2012 13:06, schrieb Erick Erickson: > What happens if you attach jconsole (should ship with your SDK) and force a > GC? > Does the extra 5G go away? > > I'm wondering if you get a couple of warming searchers going simultaneously > and happened to measure after that. > > Uwe has an interesting blog about memory, he recommends using as > little as possible, > see: > http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on-64bit.html > > Best > Erick > > On Tue, Sep 18, 2012 at 3:09 AM, Bernd Fehling > <bernd.fehl...@uni-bielefeld.de> wrote: >> Hi Otis, >> >> not really a problem because I have plenty of memory ;-) >> -Xmx25g -Xms25g -Xmn6g >> >> I'm just interested into this. >> Can you report similar jumps within JVM with your monitoring at sematext? >> >> Actually I would assume to see jumps of 0.5GB or even 1GB, but 5GB? >> And what is the cause, a cache? >> >> And is there another option in JVM to give memory jumps a size? >> >> Regards >> Bernd >> >> Am 18.09.2012 08:58, schrieb Otis Gospodnetic: >>> Hi Bernd, >>> >>> But is this really (causing) a problem? What -Xmx are you using? >>> >>> Otis >>> Search Analytics - http://sematext.com/search-analytics/index.html >>> Performance Monitoring - http://sematext.com/spm/index.html >>> >>> >>> On Tue, Sep 18, 2012 at 2:50 AM, Bernd Fehling >>> <bernd.fehl...@uni-bielefeld.de> wrote: >>>> Hi list, >>>> >>>> while monitoring my systems I see a jump in memory consumption in JVM >>>> after 2 to 5 days of running of about 5GB. >>>> >>>> After starting the system (search node only, no replication during search) >>>> SOLR uses between 6.5GB to 10.3GB of JVM when idle. >>>> If the search node is online and serves requests it uses between 7GB to >>>> 11.3GB. >>>> But after 2 to 5 days of running I see a jump in JVM with memory >>>> consumption >>>> of about 5GB. The JVM uses then between 13GB and 18GB. >>>> >>>> Anyone else seen this also? >>>> >>>> I analyzed the logs but no exceptions, no special queries, no long QTime. >>>> Also the GC log has nothing unusual at the first sight. >>>> >>>> Why is the JVM doing a jump of 5GB, which part of SOLR can cause such a >>>> jump in JVM? >>>> >>>> I would accept a slowly growing of memory consumption, but a jump? of >>>> about 5GB? >>>> >>>> Regards >>>> Bernd
