On Tue, 2015-02-17 at 11:05 +0100, Dmitry Kan wrote: > Solr: 4.10.2 (high load, mass indexing) > Java: 1.7.0_76 (Oracle) > -Xmx25600m > > > Solr: 4.3.1 (normal load, no mass indexing) > Java: 1.7.0_11 (Oracle) > -Xmx25600m > > The RAM consumption remained the same after the load has stopped on the > 4.10.2 cluster. Manually collecting the memory on a 4.10.2 shard via > jvisualvm dropped the used RAM from 8,5G to 0,5G. But the reserved RAM as > seen by top remained at 9G level.
As the JVM does not free OS memory once allocated, top just shows whatever peak it reached at some point. When you tell the JVM that it is free to use 25GB, it makes a lot of sense to allocate a fair chunk of that instead of garbage collecting if there is a period of high usage (mass indexing for example). > What else could be the artifact of such a difference -- Solr or JVM? Can it > only be explained by the mass indexing? What is worrisome is that the > 4.10.2 shard reserves 8x times it uses. If you set your Xmx to a lot less, the JVM will probably favour more frequent garbage collections over extra heap allocation. - Toke Eskildsen, State and University Library, Denmark
