Hi, all We have a search engine service built with lucene 4.7, it seem that lucene eat too much momery, and we have approximate 10 million document，the index size on disk is approximate 750G. My question is why the FST$Arc objects consume so much memory? please refer to the following histo stat of jmap. Hope anybody can give me some suggestion.
num #instances #bytes class name ---------------------------------------------- 1: 4346283 2294837424 [Lorg.apache.lucene.util.fst.FST$Arc; 2: 25918804 2023475632 [C 3: 17450041 1014051416 [B 4: 25878734 621089616 java.lang.String 5: 18634803 596313696 java.util.HashMap$Node 6: 14039862 561594480 java.util.TreeMap$Entry 7: 4346283 452013432 org.apache.lucene.util.fst.FST 8: 4522836 424741520 [Ljava.util.HashMap$Node; 9: 4346283 347702640 org.apache.lucene.codecs.BlockTreeTermsReader$FieldReader 10: 4683616 337220352 org.apache.lucene.util.fst.FST$Arc 11: 12947467 310739208 org.apache.lucene.util.BytesRef 12: 790283 280383040 [J 13: 4359111 245496264 [Ljava.lang.Object; 14: 4545337 218176176 java.util.HashMap 15: 4510384 216498432 org.apache.lucene.index.FieldInfo 16: 4359066 199713232 [I 17: 4346283 173851320 org.apache.lucene.util.fst.BytesStore 18: 4510400 144332800 java.util.Collections$UnmodifiableMap 19: 4354347 104504328 java.util.ArrayList 20: 5736589 91785424 java.lang.Integer 21: 822685 59233320 org.apache.lucene.codecs.lucene45.Lucene45DocValuesProducer$NumericEntry 22: 428313 13706016 org.apache.lucene.facet.taxonomy.writercache.CollisionMap$Entry 23: 420547 13457504 org.wltea.analyzer.dic.DictSegment 24: 177039 5665248 [Lorg.wltea.analyzer.dic.DictSegment; 25: 20 5112128 [Lorg.apache.lucene.facet.taxonomy.writercache.CollisionMap$Entry; 26: 42454 2377424 org.apache.lucene.store.RAMInputStream 27: 50054 2002160 org.apache.lucene.util.packed.Packed64 28: 44036 1761440 org.apache.lucene.util.packed.DirectPackedReader 29: 33013 1056416 java.util.concurrent.ConcurrentHashMap$Node 30: 43957 1054968 org.apache.lucene.codecs.lucene45.Lucene45DocValuesProducer$2 Thanks & Best Regards! lubin
