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From Samarendra Pratap <samarz...@gmail.com>
Subject Re: Reopening a Searcher for each request
Date Sat, 24 Apr 2010 16:25:12 GMT
No! It's not like this in my code. This code opens an IndexReader every time
I call newIndexSearcher().

In my code it is sometime like -


IndexReader[] irs;
// irs is a global array containing IndexReaders which are opened when the
application starts
.....
.....
IndexSearcher[] getIndexSearchers(IndexReader[] irs)
{
        IndexSearcher[] iss = new IndexSearcher[irs.length];
        for(int i=0;i<irs.length;i++)
        {
                iss[i] = new IndexSearcher(irs[i]);
                iss[i].setSimilarity(new MySimilarity(new
String[]{"contents"}));
        }
        return iss;
}

ParallelMultiSearcher getParallelMultiSearcher(<country and time related
parameters>) throws IOException
{
        // by checking country and time related parameters, correct elements
are chosen from complete array of IndexReaders (irs) to pass in the function
        for(int i=0;i<irs.length;i++)
        {
                if(<country and time related parameters match for current
value of "i">)
                {
                        return (new
ParallelMultiSearcher(getIndexSearchers((IndexReader[])irs[i])));
                }
        }

        // ideally this code should never be executed
        return (new
ParallelMultiSearcher(getIndexSearchers(prepareReaders(<country
and time related parameters>))));
}



2010/4/24 Ivan Liu <javacache@gmail.com>

> like this?
>  public synchronized IndexSearcher newIndexSearcher() {
>  try {
> //   semaphore.acquire();
>   if (null == indexSearcher) {
>    Directory directory = FSDirectory.open(new
> File(Config.DB_DIR+"/rssindex"));
>    indexSearcher = new IndexSearcher(IndexReader.open(directory, true));
>   } else {
>    IndexReader indexReader = indexSearcher.getIndexReader();
>    IndexReader newIndexReader = indexReader.reopen();
>    if (newIndexReader!=indexReader) {
>
>     indexReader.close();
>     indexSearcher.close();
>
>
>     indexSearcher = new IndexSearcher(newIndexReader);
>    }
>   }
>   return indexSearcher;
>  } catch (CorruptIndexException e) {
>   log.error(e.getMessage(),e);
>   return null;
>  } catch (IOException e) {
>   log.error(e.getMessage(),e);
>   return null;
>  }finally{
> //   semaphore.release();
>  }
>  }
>
> 2010/4/22 Samarendra Pratap <samarzone@gmail.com>
>
> > Thanks Mike.
> > That solved a query which was itching my mind for a long time.
> >
> > On Thu, Apr 22, 2010 at 4:41 PM, Michael McCandless <
> > lucene@mikemccandless.com> wrote:
> >
> > > It's the IndexReader that's costly to open/warm, so ideally it should
> > > be opened once and shared.
> > >
> > > The Searchers do very little on construction so re-creating per query
> > > should be OK.
> > >
> > > Mike
> > >
> > > On Thu, Apr 22, 2010 at 6:38 AM, Samarendra Pratap <
> samarzone@gmail.com>
> > > wrote:
> > > > Greetings to all.
> > > >  I have read at so many places that we should not open a Searcher for
> > > each
> > > > request for the sake of performance, but I have always been wondering
> > > > whether it is actually Searcher or Reader?
> > > >
> > > >  I have a group of index amounting to 23G which actually contains of
> > > > different index directories. The structure is something like
> following
> > > >
> > > > Main directory
> > > > |
> > > > |_________ country1
> > > > |                     |___ country1-time1 (actual index)
> > > > |                     |___ country1-time2 (actual index)
> > > > |                     |___ country1-time3 (actual index)
> > > > |
> > > > |_________ country2
> > > >                     |___ country2-time1 (actual index)
> > > >                     |___ country2-time2 (actual index)
> > > >                     |___ country2-time3 (actual index)
> > > >
> > > >  When application starts I open IndexReaders on all of actual index
> > > > directories (country1-time1, country1-tim2, .... country2-time3) and
> > keep
> > > > them in a pool.
> > > >
> > > >  At the time of search, IndexSearchers are created by selecting the
> > > > appropriate IndexReaders from the pool. These IndexSearchers in turn
> > are
> > > > used to create a ParallelMultiSearcher. Constructors of IndexSearcher
> > and
> > > > ParallelMultiSearcher are run for every request.
> > > >
> > > >  Now I believe that creating a pool of ParallelMultiSearcher itself
> is
> > a
> > > > good idea but* I wanted to know if reopening **IndexSearchers** will
> > > really
> > > > degrade performance irrespective of **IndexReaders** being opened
> > once*.
> > > >
> > > > In my performance tests (which may not be very comprehensive) I
> didn't
> > > find
> > > > any noticeable difference.
> > > >
> > > > Please throw some light.
> > > >
> > > >
> > > > --
> > > > Regards,
> > > > Samar
> > > >
> > >
> > > ---------------------------------------------------------------------
> > > To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> > > For additional commands, e-mail: java-user-help@lucene.apache.org
> > >
> > >
> >
> >
> > --
> > Regards,
> > Samar
> >
>
>
>
> --
> 冲浪板
>
> my blog:冲浪板 <http://chonglangban.appspot.com/>
> my site:Keji Technology <http://kejiblog.appspot.com/>
>



-- 
Regards,
Samar

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