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From "Nik Everett (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-6046) RegExp.toAutomaton high memory use
Date Mon, 03 Nov 2014 20:53:33 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-6046?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14195065#comment-14195065
] 

Nik Everett commented on LUCENE-6046:
-------------------------------------

I'll certainly add the regexp string to the exception message.  And I'll merge the toStringTree
from your patch into mine if you'd like.

Yeah - QueryParserBase should have this option too.

The thing I found most useful for debugging this was to call toDot on the automata before
and after normalization.  I just looked at it and went, oh, of course you have to do it that
way.  No wonder the states explode.  And then I read https://en.wikipedia.org/wiki/Powerset_construction
and remembered it from my rusty CS degree.

> RegExp.toAutomaton high memory use
> ----------------------------------
>
>                 Key: LUCENE-6046
>                 URL: https://issues.apache.org/jira/browse/LUCENE-6046
>             Project: Lucene - Core
>          Issue Type: Bug
>          Components: core/queryparser
>    Affects Versions: 4.10.1
>            Reporter: Lee Hinman
>            Assignee: Michael McCandless
>            Priority: Minor
>         Attachments: LUCENE-6046.patch, LUCENE-6046.patch
>
>
> When creating an automaton from an org.apache.lucene.util.automaton.RegExp, it's possible
for the automaton to use so much memory it exceeds the maximum array size for java.
> The following caused an OutOfMemoryError with a 32gb heap:
> {noformat}
> new RegExp("\\[\\[(Datei|File|Bild|Image):[^]]*alt=[^]|}]{50,200}").toAutomaton();
> {noformat}
> When increased to a 60gb heap, the following exception is thrown:
> {noformat}
>   1> java.lang.IllegalArgumentException: requested array size 2147483624 exceeds maximum
array in java (2147483623)
>   1>     __randomizedtesting.SeedInfo.seed([7BE81EF678615C32:95C8057A4ABA5B52]:0)
>   1>     org.apache.lucene.util.ArrayUtil.oversize(ArrayUtil.java:168)
>   1>     org.apache.lucene.util.ArrayUtil.grow(ArrayUtil.java:295)
>   1>     org.apache.lucene.util.automaton.Automaton$Builder.addTransition(Automaton.java:639)
>   1>     org.apache.lucene.util.automaton.Operations.determinize(Operations.java:741)
>   1>     org.apache.lucene.util.automaton.MinimizationOperations.minimizeHopcroft(MinimizationOperations.java:62)
>   1>     org.apache.lucene.util.automaton.MinimizationOperations.minimize(MinimizationOperations.java:51)
>   1>     org.apache.lucene.util.automaton.RegExp.toAutomaton(RegExp.java:477)
>   1>     org.apache.lucene.util.automaton.RegExp.toAutomaton(RegExp.java:426)
> {noformat}



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