A ballpark calculation would be Collected Amount (From GC logging)/ # of Requests.
The GC logging can tell you how much it collected each time, no need to try and snapshot before and after heap sizes. However (big caveat here), this is a ballpark figure. The garbage collector is not guaranteed to collect everything, every time. It can stop collecting depending on how much time it spent. It may only collect from certain sections within memory (Eden, survivor, tenured), etc. This may still be enough to make broad comparisons to see if you've decreased the overall garbage/request (via cache changes), but it will be quite a rough estimate. -Todd -----Original Message----- From: wojtekpia [mailto:wojte...@hotmail.com] Sent: Wednesday, January 21, 2009 3:08 PM To: solr-user@lucene.apache.org Subject: Re: Performance "dead-zone" due to garbage collection (Thanks for the responses) My filterCache hit rate is ~60% (so I'll try making it bigger), and I am CPU bound. How do I measure the size of my per-request garbage? Is it (total heap size before collection - total heap size after collection) / # of requests to cause a collection? I'll try your suggestions and post back any useful results. -- View this message in context: http://www.nabble.com/Performance-%22dead-zone%22-due-to-garbage-collect ion-tp21588427p21593661.html Sent from the Solr - User mailing list archive at Nabble.com.
