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Posted to issues@lucene.apache.org by "Tomoko Uchida (Jira)" <ji...@apache.org> on 2022/05/08 07:10:00 UTC

[jira] [Updated] (LUCENE-10059) Assertion error in JapaneseTokenizer / KoreanTokenizer backtrace

     [ https://issues.apache.org/jira/browse/LUCENE-10059?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tomoko Uchida updated LUCENE-10059:
-----------------------------------
    Summary: Assertion error in JapaneseTokenizer / KoreanTokenizer backtrace  (was: Assertion error in JapaneseTokenizer backtrace)

> Assertion error in JapaneseTokenizer / KoreanTokenizer backtrace
> ----------------------------------------------------------------
>
>                 Key: LUCENE-10059
>                 URL: https://issues.apache.org/jira/browse/LUCENE-10059
>             Project: Lucene - Core
>          Issue Type: Bug
>    Affects Versions: 8.8
>            Reporter: Anh Dung Bui
>            Priority: Major
>             Fix For: 8.x, 9.0
>
>         Attachments: LUCENE-10059-nori-9x.patch
>
>          Time Spent: 1h 40m
>  Remaining Estimate: 0h
>
> There is a rare case which causes an AssertionError in the backtrace step of JapaneseTokenizer that we (Amazon Product Search) found in our tests.
> If there is a text span of length 1024 (determined by [MAX_BACKTRACE_GAP|https://github.com/apache/lucene/blob/main/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/JapaneseTokenizer.java#L116]) where the regular backtrace is not called, a [forced backtrace|https://github.com/apache/lucene/blob/main/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/JapaneseTokenizer.java#L781] will be applied. If the partially best path at this point happens to end at the last pos, and since there is always a [final backtrace|https://github.com/apache/lucene/blob/main/lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/JapaneseTokenizer.java#L1044] applied at the end, the final backtrace will try to backtrace from and to the same position, causing an AssertionError in RollingCharBuffer.get() when it tries to generate an empty buffer.
> We are fixing it by returning prematurely in the backtrace() method when the from and to pos are the same:
> {code:java}
>     if (endPos == lastBackTracePos) {
>       return;
>     }
> {code}
> The backtrace() method is essentially no-op when this condition happens, thus when _-ea_ is not enabled, it can still output the correct tokens.
> We will open a PR for this issue.



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