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Date: Fri, 3 Jun 2011 17:57:48 +0000 (UTC)
From: "Robert Muir (JIRA)" <jira@apache.org>
To: dev@lucene.apache.org
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Subject: [jira] [Commented] (SOLR-2462) Using spellcheck.collate can result
 in extremely high memory usage
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    [ https://issues.apache.org/jira/browse/SOLR-2462?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13043913#comment-13043913 ] 

Robert Muir commented on SOLR-2462:
-----------------------------------

Hi, this is looking much better!

To eliminate your last concerns, I think what is needed is a tie-breaker in RankedSpellPossibility's comparator, ideally something like a sequential identifier.

This way, when the PQ fills, and the lowest score is 20, then subsequent items that also have a score of 20 will not be competitive, and rejected by the competitive check... remember peek() is constant time :)

This is the way Lucene collectors work (tiebreaker is lucene docid), and the way e.g. FuzzyQuery/FuzzyLikeThisQuery works (tiebreaker is term text)


> Using spellcheck.collate can result in extremely high memory usage
> ------------------------------------------------------------------
>
>                 Key: SOLR-2462
>                 URL: https://issues.apache.org/jira/browse/SOLR-2462
>             Project: Solr
>          Issue Type: Bug
>          Components: spellchecker
>    Affects Versions: 3.1
>            Reporter: James Dyer
>            Priority: Critical
>             Fix For: 3.1.1, 4.0
>
>         Attachments: SOLR-2462.patch, SOLR-2462.patch, SOLR-2462.patch, SOLR-2462.patch, SOLR-2462.patch, SOLR-2462.patch, SOLR-2462_3_1.patch
>
>
> When using "spellcheck.collate", class SpellPossibilityIterator creates a ranked list of *every* possible correction combination.  But if returning several corrections per term, and if several words are misspelled, the existing algorithm uses a huge amount of memory.
> This bug was introduced with SOLR-2010.  However, it is triggered anytime "spellcheck.collate" is used.  It is not necessary to use any features that were added with SOLR-2010.
> We were in Production with Solr for 1 1/2 days and this bug started taking our Solr servers down with "infinite" GC loops.  It was pretty easy for this to happen as occasionally a user will accidently paste the URL into the Search box on our app.  This URL results in a search with ~12 misspelled words.  We have "spellcheck.count" set to 15. 

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