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From "Andy Seaborne (JIRA)" <>
Subject [jira] Reopened: (JENA-5) IndexLARQ is not thread safe
Date Wed, 29 Dec 2010 17:51:47 GMT


Andy Seaborne reopened JENA-5:

> IndexLARQ is not thread safe
> ----------------------------
>                 Key: JENA-5
>                 URL:
>             Project: Jena
>          Issue Type: Bug
>          Components: ARQ
>            Reporter: Brian McBride
>            Assignee: Andy Seaborne
>         Attachments:, larqConcurrentPatch,
> Copying a previously sent email:
> I ran into a concurrency problem in LARQ.  When I try to run concurrent queries the Lucene
query parser barfs.
> After a bit of digging, I think I understand what is going on.  I was creating  an IndexLARQ
and setting that as the global index, then running my queries.  The IndexLARQ constructor
constructs a Lucene QueryParser object which it uses for all queries.  Lucene QueryParser
objects are not thread safe, so multiple concurrent queries cause the parser the barf.
> I have had a go at patching the HEAD from SVN.  Basically I make the QueryParser object
in IndexLARQ ThreadLocal.
> The problem with this is that there is a constructor to IndexLARQ which takes an externally
provided QueryParser object and QueryParser is not clonable.  I could replicate the query
parser for each thread provided I know its a QueryParser and not a subclass of QueryParser.
 If someone passed in a subclass of QueryParser I'd go creating the wrong class of objects
as a replica.
> Whilst this scenario is not very likely, since I think the constructor should be deprecated
anyway, what I've done is esentially left that constructor alone.  Creating an IndexLARQ with
that contructor will continue to construct one that is not thread safe.  The other constructors
will construct threadsafe instances.
> Attached are:
> a modified that fixes the problem as I've described.
> - a test case
> larqConcurrentPatch - a patch file that applies the changes
> Oops - Just noticed the license notice on the test case file - you will want to change
that if you use this. 
> hmmm - there doesn't seem to be a button here for attaching files.

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