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https://issues.apache.org/jira/browse/LUCENE-5897?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14136403#comment-14136403
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Michael McCandless commented on LUCENE-5897:
--------------------------------------------

Hmm ... merge conflicts on backport ... [~sar...@syr.edu] maybe you can try to 
backport?  The conflicts seem to be only in the autogen'd sources so maybe I 
just need to backport and regen?

> performance bug ("adversary") in StandardTokenizer
> --------------------------------------------------
>
>                 Key: LUCENE-5897
>                 URL: https://issues.apache.org/jira/browse/LUCENE-5897
>             Project: Lucene - Core
>          Issue Type: Bug
>            Reporter: Robert Muir
>            Assignee: Steve Rowe
>             Fix For: 4.10, 5.0, 4.9.1
>
>         Attachments: LUCENE-5897.patch
>
>
> There seem to be some conditions (I don't know how rare or what conditions) 
> that cause StandardTokenizer to essentially hang on input: I havent looked 
> hard yet, but as its essentially a DFA I think something wierd might be going 
> on.
> An easy way to reproduce is with 1MB of underscores, it will just hang 
> forever.
> {code}
>   public void testWorthyAdversary() throws Exception {
>     char buffer[] = new char[1024 * 1024];
>     Arrays.fill(buffer, '_');
>     int tokenCount = 0;
>     Tokenizer ts = new StandardTokenizer();
>     ts.setReader(new StringReader(new String(buffer)));
>     ts.reset();
>     while (ts.incrementToken()) {
>       tokenCount++;
>     }
>     ts.end();
>     ts.close();
>     assertEquals(0, tokenCount);
>   }
> {code} 



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