On 7/24/2016 11:13 PM, Madhur Adlakha wrote: > To whom so ever it may concern, > > I have been fetching certain Solr metrics and keeping a track of them > graphically on Grafana, there are a few queries I wanted to clear, as follows: > > * How and which metrics of Solr are affected by the Garbage collector? > * Which metrics of garbage collector should we track that might have > implications on Solr?
Garbage collection can result in a complete pause of the Java virtual machine. This pause can be quite long -- I've seen 15-20 seconds in a single full GC pause in a running Solr 4.x install with no GC tuning. When this happens, Java *only* does garbage collection. *ANYTHING* that Solr is doing when the pause occurs will be delayed, so any performance metric might be affected. Pause time is what you need to track. When there are GC logs, you can load those logs into GCViewer and get a lot of statistics. https://github.com/chewiebug/GCViewer Another good tool for calculating JVM pauses from *any* source is jHiccup. https://www.azul.com/jhiccup/ The start script in Solr 5.0 and later has default GC tuning parameters that work pretty well for typical heap sizes of a few gigabytes. If you have a particularly large heap, you may need different GC tuning. I have done some work on G1 tuning parameters. https://wiki.apache.org/solr/ShawnHeisey#GC_Tuning_for_Solr Thanks, Shawn
