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https://issues.apache.org/jira/browse/LUCENE-2279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12837373#action_12837373
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thushara wijeratna commented on LUCENE-2279:
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isn't the resusableTokenStream created again for a new Document, while there is
no need to copy the list of stopwords for a new document? or did i miss
something?
> eliminate pathological performance on StopFilter when using a Set<String>
> instead of CharArraySet
> -------------------------------------------------------------------------------------------------
>
> Key: LUCENE-2279
> URL: https://issues.apache.org/jira/browse/LUCENE-2279
> Project: Lucene - Java
> Issue Type: Improvement
> Reporter: thushara wijeratna
>
> passing a Set<Srtring> to a StopFilter instead of a CharArraySet results in a
> very slow filter.
> this is because for each document, Analyzer.tokenStream() is called, which
> ends up calling the StopFilter (if used). And if a regular Set<String> is
> used in the StopFilter all the elements of the set are copied to a
> CharArraySet, as we can see in it's ctor:
> public StopFilter(boolean enablePositionIncrements, TokenStream input, Set
> stopWords, boolean ignoreCase)
> {
> super(input);
> if (stopWords instanceof CharArraySet) {
> this.stopWords = (CharArraySet)stopWords;
> } else {
> this.stopWords = new CharArraySet(stopWords.size(), ignoreCase);
> this.stopWords.addAll(stopWords);
> }
> this.enablePositionIncrements = enablePositionIncrements;
> init();
> }
> i feel we should make the StopFilter signature specific, as in specifying
> CharArraySet vs Set, and there should be a JavaDoc warning on using the other
> variants of the StopFilter as they all result in a copy for each invocation
> of Analyzer.tokenStream().
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