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Message-Id: <68C36A6A-9107-48A6-9DCC-74CA92B9CF0E@mikemccandless.com>
From: Michael McCandless <lucene@mikemccandless.com>
To: java-user@lucene.apache.org
In-Reply-To: <6d6cf45b0810151029w192c16f5kf869d267f3194c17@mail.gmail.com>
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Subject: Re: Closing Index Reader
Date: Wed, 15 Oct 2008 13:48:19 -0400
References: <6d6cf45b0810141935j4d7fb29cj6e323b40a39d8381@mail.gmail.com>
 <01c701c92ea4$0c063f20$330bc30a@sv.us.sonicwall.com>
 <3499CAC1-6382-4EDE-BDCC-9A952A39A742@mikemccandless.com>
 <01cf01c92ead$566131c0$330bc30a@sv.us.sonicwall.com>
 <BFE538E2-949B-462B-9C6E-99AC8AE5E00A@mikemccandless.com>
 <6d6cf45b0810151029w192c16f5kf869d267f3194c17@mail.gmail.com>


That is correct, as long as you incRef the reader before starting each  
query, and decRef the reader after finishing each query.

If you call close() during this time, the reader is not actually  
closed until decRef is called for all previous incRefs.

Be certain that once you close() a reader there is no way a new query  
can grab that reader.  That would be a thread hazard that could result  
in using an already closed reader.

Also be certain you always decRef, eg in a finally clause.

Mike

Khawaja Shams wrote:

> Hello,   Thank you for your ideas. While these look promising, it  
> seems like
> there are many places within Lucene's codebase that are invoking the  
> incRef
> and decRef methods.  Upon a shallow analysis of the code, it seems  
> like I
> can call close, and the doClose method does not get called until  
> refCount is
> 0.  Can anyone correct or confirm my assumption that you can call  
> close and
> any query in progress as you call close will succeed because the  
> reader
> won't be closed until the refCount is 0.  Thanks again!
>
> On Wed, Oct 15, 2008 at 3:10 AM, Michael McCandless <
> lucene@mikemccandless.com> wrote:
>
>>
>> As of 2.4.0 they are public.
>>
>> Mike
>>
>>
>> Ganesh wrote:
>>
>> incRef/decRef  methods are protected. Is there any other way to use  
>> these
>>> methods without extending it?
>>>
>>> Regards
>>> Ganesh
>>>
>>> ----- Original Message ----- From: "Michael McCandless" <
>>> lucene@mikemccandless.com>
>>> To: <java-user@lucene.apache.org>
>>> Sent: Wednesday, October 15, 2008 2:31 PM
>>> Subject: Re: Closing Index Reader
>>>
>>>
>>>
>>>> Ganesh wrote:
>>>>
>>>> Yes. Once the Indexreader is closed, you should not do make any   
>>>> calls
>>>>> with that object.
>>>>> Extend the IndexReader to add support for reference count. Close  
>>>>> the
>>>>> reader once the count is zero.
>>>>>
>>>>
>>>> Actually you can just use the [expert] incRef/decRef methods on
>>>> IndexReader to track in-flight searches still using it.  You  
>>>> shouldn't have
>>>> to extend it.
>>>>
>>>> Mike
>>>>
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