hi , after upgrading to Lucune 3.6.2 i noticed there is an extensive minor garbage collection operations. once or twice a second , and the amount of memory being freed is about 600 MB each time for a load of 60 searches per second :
2013-01-09T18:57:24.350+0200: 174200.121: [GC [PSYoungGen: 630064K->544K(630336K)] 1405948K->776747K(1660992K), 0.0084250 secs] [Times: user=0.03 sys=0.00, real=0.01 secs] 2013-01-09T18:57:24.785+0200: 174200.555: [GC [PSYoungGen: 629920K->704K(630336K)] 1406123K->777083K(1660992K), 0.0066510 secs] [Times: user=0.04 sys=0.00, real=0.01 secs] after some investigation , the caused seemed to be Lucune related , we are using RAM directory (with about 70000 documents ) on top of tomcat 7. so i took Lucune source code and integrated it to our application , then run Jprofiler during some load for a minute and checked the "application call tree " for "Garbage collected objects" only . i found that the 2 Lucune method that produce the most garbage collected object are (*screen shot attached* ) : (we have several indexes the below is from one of them ) - 23.2% - 215 MB - 48,252 alloc. org.apache.lucene.search.ExactPhraseScorer. - 6.3% - 60,481 kB - 728,414 alloc. org.apache.lucene.search.BooleanQuery$BooleanWeight.scorer looking at the currently live object i see the top 2 classes instance are ( a screen shot is also attached ) : org.apache.lucene.search.BooleanScorer$Bucket (instance count ) 1311699 (size) 41974368 org.apache.lucene.search.ScoreDoc (instance count )45846 (size)1100304 we have a system with an earlier version (tomcat 5.5 and Lucune 3.0.3 our all other code / jars are the same) which handles the same load and has the same indexes and the minor gc there occurs once every 1-2 second and the amount of memory being freed is about 60 MB. does this behavior is normal ? does a search should really generate so much short lived objects ( about 5MB for a search ) ? should we try and use some other RAM bases Index ? ( i know InstantiatedIndex is deprecated ) thanks in advance . Alon
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