Memory Leak when using Custom Sort (i.e., DistanceSortSource) of LocalLucene
with Lucene
----------------------------------------------------------------------------------------
Key: LUCENE-1304
URL: https://issues.apache.org/jira/browse/LUCENE-1304
Project: Lucene - Java
Issue Type: Bug
Components: Search
Affects Versions: 2.3
Environment: Windows/JDK 1.6
Reporter: Ethan Tao
We had the memory leak issue when using DistanceSortSource of LocalLucene for
repeated query/search. In about 450 queries, we are experiencing out of memory
error. After dig in the code, we found the problem source is coming from Lucene
package, the way how it handles "custom" type comparator. Lucene internally
caches all created comparators. In the case of query using LocalLucene, we
create new comparator for every search due to different lon/lat and query
terms. This causes major memory leak as the cached comparators are also holding
memory for other large objects (e.g., bit sets). The solution we came up with:
( the proposed change from Lucene is 1 and 3 below)
1. In Lucene package, create new file SortComparatorSourceUncacheable.java:
package org.apache.lucene.search;
import org.apache.lucene.index.IndexReader;
import java.io.IOException;
import java.io.Serializable;
public interface SortComparatorSourceUncacheable extends Serializable {
}
2. Have your custom sort class to implement the interface
public class LocalSortSource extends DistanceSortSource implements
SortComparatorSourceUncacheable {
...
}
3. Modify Lucene's FieldSorterHitQueue.java to bypass caching for custom
sort comparator:
Index: FieldSortedHitQueue.java
===================================================================
--- FieldSortedHitQueue.java (revision 654583)
+++ FieldSortedHitQueue.java (working copy)
@@ -53,7 +53,12 @@
this.fields = new SortField[n];
for (int i=0; i<n; ++i) {
String fieldname = fields[i].getField();
- comparators[i] = getCachedComparator (reader, fieldname,
fields[i].getType(), fields[i].getLocale(), fields[i].getFactory());
+
+ if(fields[i].getFactory() instanceof SortComparatorSourceUncacheable) {
// no caching to avoid memory leak
+ comparators[i] = getComparator (reader, fieldname,
fields[i].getType(), fields[i].getLocale(), fields[i].getFactory());
+ } else {
+ comparators[i] = getCachedComparator (reader, fieldname,
fields[i].getType(), fields[i].getLocale(), fields[i].getFactory());
+ }
if (comparators[i].sortType() == SortField.STRING) {
this.fields[i] = new SortField (fieldname,
fields[i].getLocale(), fields[i].getReverse());
@@ -157,7 +162,18 @@
SortField[] getFields() {
return fields;
}
-
+
+ static ScoreDocComparator getComparator (IndexReader reader, String field,
int type, Locale locale, SortComparatorSource factory)
+ throws IOException {
+ if (type == SortField.DOC) return ScoreDocComparator.INDEXORDER;
+ if (type == SortField.SCORE) return ScoreDocComparator.RELEVANCE;
+ FieldCacheImpl.Entry entry = (factory != null)
+ ? new FieldCacheImpl.Entry (field, factory)
+ : new FieldCacheImpl.Entry (field, type, locale);
+ return (ScoreDocComparator)Comparators.createValue(reader, entry);
+ }
+
+
Otis suggests that I put this in Jira. I 'll attach a patch shortly for review.
-Ethan
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