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https://issues.apache.org/jira/browse/LUCENE-8662?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16754984#comment-16754984
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Simon Willnauer commented on LUCENE-8662:
-----------------------------------------
{noformat}
If we think that it's a trap, we should remove the default impl and make it
abstract (in 8.0).
{noformat}
I agree with this. I think it can be trappy and such an expert API shouldn't.
Let make it abstract?
> Override seekExact(BytesRef) in FilterLeafReader.FilterTermsEnum
> ----------------------------------------------------------------
>
> Key: LUCENE-8662
> URL: https://issues.apache.org/jira/browse/LUCENE-8662
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/search
> Affects Versions: 5.5.5, 6.6.5, 7.6, 8.0
> Reporter: jefferyyuan
> Priority: Major
> Labels: query
> Fix For: 8.0, 7.7
>
> Attachments: output of test program.txt
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Recently in our production, we found that Sole uses a lot of memory(more than
> 10g) during recovery or commit for a small index (3.5gb)
> The stack trace is:
>
> {code:java}
> Thread 0x4d4b115c0
> at org.apache.lucene.store.DataInput.readVInt()I (DataInput.java:125)
> at org.apache.lucene.codecs.blocktree.SegmentTermsEnumFrame.loadBlock()V
> (SegmentTermsEnumFrame.java:157)
> at
> org.apache.lucene.codecs.blocktree.SegmentTermsEnumFrame.scanToTermNonLeaf(Lorg/apache/lucene/util/BytesRef;Z)Lorg/apache/lucene/index/TermsEnum$SeekStatus;
> (SegmentTermsEnumFrame.java:786)
> at
> org.apache.lucene.codecs.blocktree.SegmentTermsEnumFrame.scanToTerm(Lorg/apache/lucene/util/BytesRef;Z)Lorg/apache/lucene/index/TermsEnum$SeekStatus;
> (SegmentTermsEnumFrame.java:538)
> at
> org.apache.lucene.codecs.blocktree.SegmentTermsEnum.seekCeil(Lorg/apache/lucene/util/BytesRef;)Lorg/apache/lucene/index/TermsEnum$SeekStatus;
> (SegmentTermsEnum.java:757)
> at
> org.apache.lucene.index.FilterLeafReader$FilterTermsEnum.seekCeil(Lorg/apache/lucene/util/BytesRef;)Lorg/apache/lucene/index/TermsEnum$SeekStatus;
> (FilterLeafReader.java:185)
> at
> org.apache.lucene.index.TermsEnum.seekExact(Lorg/apache/lucene/util/BytesRef;)Z
> (TermsEnum.java:74)
> at
> org.apache.solr.search.SolrIndexSearcher.lookupId(Lorg/apache/lucene/util/BytesRef;)J
> (SolrIndexSearcher.java:823)
> at
> org.apache.solr.update.VersionInfo.getVersionFromIndex(Lorg/apache/lucene/util/BytesRef;)Ljava/lang/Long;
> (VersionInfo.java:204)
> at
> org.apache.solr.update.UpdateLog.lookupVersion(Lorg/apache/lucene/util/BytesRef;)Ljava/lang/Long;
> (UpdateLog.java:786)
> at
> org.apache.solr.update.VersionInfo.lookupVersion(Lorg/apache/lucene/util/BytesRef;)Ljava/lang/Long;
> (VersionInfo.java:194)
> at
> org.apache.solr.update.processor.DistributedUpdateProcessor.versionAdd(Lorg/apache/solr/update/AddUpdateCommand;)Z
> (DistributedUpdateProcessor.java:1051)
> {code}
> We reproduced the problem locally with the following code using Lucene code.
> {code:java}
> public static void main(String[] args) throws IOException {
> FSDirectory index = FSDirectory.open(Paths.get("the-index"));
> try (IndexReader reader = new
> ExitableDirectoryReader(DirectoryReader.open(index),
> new QueryTimeoutImpl(1000 * 60 * 5))) {
> String id = "the-id";
> BytesRef text = new BytesRef(id);
> for (LeafReaderContext lf : reader.leaves()) {
> TermsEnum te = lf.reader().terms("id").iterator();
> System.out.println(te.seekExact(text));
> }
> }
> }
> {code}
>
> I added System.out.println("ord: " + ord); in
> codecs.blocktree.SegmentTermsEnum.getFrame(int).
> Please check the attached output of test program.txt.
>
> We found out the root cause:
> we didn't implement seekExact(BytesRef) method in
> FilterLeafReader.FilterTerms, so it uses the base class
> TermsEnum.seekExact(BytesRef) implementation which is very inefficient in
> this case.
> {code:java}
> public boolean seekExact(BytesRef text) throws IOException {
> return seekCeil(text) == SeekStatus.FOUND;
> }
> {code}
> The fix is simple, just override seekExact(BytesRef) method in
> FilterLeafReader.FilterTerms
> {code:java}
> @Override
> public boolean seekExact(BytesRef text) throws IOException {
> return in.seekExact(text);
> }
> {code}
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