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From Cheng <zhoucheng2...@gmail.com>
Subject Re: Configure writer to write to FSDirectory?
Date Mon, 06 Feb 2012 15:45:13 GMT
Uwe, when I meant speed is slow, I didn't refer to instant visibility of
changes, but that the changes may be synchronized with FSDirectory when I
use writer.commit().

When I use RAMDirectory, the writer.commit() seems much faster than using
NRTManager built upon FSDirectory. So, I am guessing the difference is the
index synchronization.



On Mon, Feb 6, 2012 at 11:40 PM, Uwe Schindler <uwe@thetaphi.de> wrote:

> Please review the following articles about NRT, absolutely instant updates
> that are visible as they are done are almost impossible (even with
> RAMDirectory):
>
> http://goo.gl/mzAHt
> http://goo.gl/5RoPx
> http://goo.gl/vSJ7x
>
> Uwe
>
> -----
> Uwe Schindler
> H.-H.-Meier-Allee 63, D-28213 Bremen
> http://www.thetaphi.de
> eMail: uwe@thetaphi.de
>
> > -----Original Message-----
> > From: Cheng [mailto:zhoucheng2008@gmail.com]
> > Sent: Monday, February 06, 2012 4:27 PM
> > To: java-user@lucene.apache.org
> > Subject: Re: Configure writer to write to FSDirectory?
> >
> > Ian,
> >
> > I encountered an issue that I need to frequently update the index. The
> > NRTManager seems not very helpful on this front as the speed is slower
> than
> > RAMDirectory is used.
> >
> > Any improvement advice?
> >
> >
> >
> > On Mon, Feb 6, 2012 at 10:24 PM, Cheng <zhoucheng2008@gmail.com> wrote:
> >
> > > That really helps! I will try it out.
> > >
> > > Thanks.
> > >
> > >
> > > On Mon, Feb 6, 2012 at 10:12 PM, Ian Lea <ian.lea@gmail.com> wrote:
> > >
> > >> You would use NRTManagerReopenThread as a standalone thread, not
> > >> plugged into your Executor stuff.  It is a utility class which you
> > >> don't have to use.  See the javadocs.
> > >>
> > >> But in your case I'd use it, to start with anyway.  Fire it up with
> > >> suitable settings and forget about it, except to call close()
> > >> eventually. Once you've got things up and running you can tweak
> > >> things as much as you want but you appear to be having trouble
> > >> getting up and running.
> > >>
> > >> So ... somewhere in the initialisation code of your app, create an
> > >> IndexWriter, NRTManager + ReopenThread and SearcherManager as
> > >> outlined before.  Then pass the NRTManager to any/all write methods
> > >> or threads and the SearcherManager instance to any/all search methods
> > >> or threads and you're done.  If you want to use threads that are part
> > >> of your ExecutorService, fine.  Just wrap it all together in whatever
> > >> combination of Thread or Runnable instances you want.
> > >>
> > >>
> > >> Does that help?
> > >>
> > >>
> > >> --
> > >> Ian.
> > >>
> > >>
> > >> > I don't understand this following portion:
> > >> >
> > >> > IndexWriter iw = new IndexWriter(whatever - some standard disk
> > >> > index); NRTManager nrtm = new NRTManager(iw, null);
> > >> > NRTManagerReopenThread ropt = new NRTManagerReopenThread(nrtm,
> > >> > ...); ropt.setXxx(...); ....
> > >> > ropt.start();
> > >> >
> > >> > I have a java ExecutorServices instance running which take care of
> > >> > my
> > >> own
> > >> > applications. I don't know how this NRTManagerReopenThread works
> > >> > with my own ExecutorService instance.
> > >> >
> > >> > Can both work together? How can the NRTManagerReopenThread
> > instance
> > >> ropt be
> > >> > plugged into my own multithreading framework?
> > >> >
> > >> > On Mon, Feb 6, 2012 at 8:17 PM, Ian Lea <ian.lea@gmail.com>
wrote:
> > >> >
> > >> >> If you can use NRTManager and SearcherManager things should be
> > >> >> easy and blazingly fast rather than unbearably slow.  The latter
> > >> >> phrase is not one often associated with lucene.
> > >> >>
> > >> >> IndexWriter iw = new IndexWriter(whatever - some standard disk
> > >> >> index); NRTManager nrtm = new NRTManager(iw, null);
> > >> >> NRTManagerReopenThread ropt = new
> > NRTManagerReopenThread(nrtm,
> > >> >> ...); ropt.setXxx(...); ...
> > >> >> ropt.start();
> > >> >>
> > >> >> SearcherManager srchm = nrtm.getSearcherManager(b);
> > >> >>
> > >> >> Then add docs to your index via nrtm.addDocument(d), update with
> > >> >> nrtm.updateDocument(...), and to search use
> > >> >>
> > >> >> IndexSearcher searcher = srchm.acquire(); try {  search ...
> > >> >> } finally {
> > >> >>  srchm.release(searcher);
> > >> >> }
> > >> >>
> > >> >> All thread safe so you don't have to worry about any complications
> > >> >> there.  And I bet it'll be blindingly fast.
> > >> >>
> > >> >> Don't forget to close() things down at the end.
> > >> >>
> > >> >>
> > >> >> --
> > >> >> Ian.
> > >> >>
> > >> >>
> > >> >>
> > >> >> On Mon, Feb 6, 2012 at 12:15 AM, Cheng <zhoucheng2008@gmail.com>
> > >> wrote:
> > >> >> > I was trying to, but don't know how to even I read some of
your
> > >> blogs.
> > >> >> >
> > >> >> > On Sun, Feb 5, 2012 at 10:22 PM, Michael McCandless <
> > >> >> > lucene@mikemccandless.com> wrote:
> > >> >> >
> > >> >> >> Are you using near-real-time readers?
> > >> >> >>
> > >> >> >> (IndexReader.open(IndexWriter))
> > >> >> >>
> > >> >> >> Mike McCandless
> > >> >> >>
> > >> >> >> http://blog.mikemccandless.com
> > >> >> >>
> > >> >> >> On Sun, Feb 5, 2012 at 9:03 AM, Cheng <zhoucheng2008@gmail.com>
> > >> wrote:
> > >> >> >> > Hi Uwe,
> > >> >> >> >
> > >> >> >> > My challenge is that I need to update/modify the
indexes
> > >> frequently
> > >> >> while
> > >> >> >> > providing the search capability. I was trying to
use
> > >> >> >> > FSDirectory,
> > >> but
> > >> >> >> found
> > >> >> >> > out that the reading and writing from/to FSDirectory
is
> > >> >> >> > unbearably
> > >> >> slow.
> > >> >> >> So
> > >> >> >> > I now am trying the RAMDirectory, which is fast.
> > >> >> >> >
> > >> >> >> > I don't know of  MMapDirectory, and wonder if it
is as fast
> > >> >> >> > as
> > >> >> >> RAMDirectory.
> > >> >> >> >
> > >> >> >> >
> > >> >> >> > On Sun, Feb 5, 2012 at 4:14 PM, Uwe Schindler
> > >> >> >> > <uwe@thetaphi.de>
> > >> >> wrote:
> > >> >> >> >
> > >> >> >> >> Hi Cheng,
> > >> >> >> >>
> > >> >> >> >> It seems that you use a RAMDirectory for *caching*,
> > >> >> >> >> otherwise it
> > >> >> makes
> > >> >> >> no
> > >> >> >> >> sense to write changes back. In recent Lucene
versions, this
> > >> >> >> >> is
> > >> not a
> > >> >> >> good
> > >> >> >> >> idea, especially for large indexes (RAMDirectory
eats your
> > >> >> >> >> heap
> > >> >> space,
> > >> >> >> >> allocates millions of small byte[] arrays,...).
If you need
> > >> something
> > >> >> >> like
> > >> >> >> >> a
> > >> >> >> >> caching Directory and you are working on a 64bit
platform,
> > >> >> >> >> you
> > >> can
> > >> >> use
> > >> >> >> >> MMapDirectory (where the operating system kernel
manages the
> > >> >> read/write
> > >> >> >> >> between disk an memory). MMapDirectory is returned
by
> > >> >> >> >> default for
> > >> >> >> >> FSDirectory.open() on most 64 bit platforms.
The good thing:
> > >> >> >> >> the
> > >> >> >> "caching"
> > >> >> >> >> space is outside your JVM heap, so does not
slowdown the
> > >> >> >> >> garbage
> > >> >> >> collector.
> > >> >> >> >> So be sure to *not* allocate too much heap space
(-Xmx) to
> > >> >> >> >> your
> > >> >> search
> > >> >> >> app,
> > >> >> >> >> only the minimum needed to execute it and leave
the rest of
> > >> >> >> >> your
> > >> RAM
> > >> >> >> >> available for the OS kernel to manage FS cache.
> > >> >> >> >>
> > >> >> >> >> Uwe
> > >> >> >> >>
> > >> >> >> >> -----
> > >> >> >> >> Uwe Schindler
> > >> >> >> >> H.-H.-Meier-Allee 63, D-28213 Bremen http://www.thetaphi.de
> > >> >> >> >> eMail: uwe@thetaphi.de
> > >> >> >> >>
> > >> >> >> >>
> > >> >> >> >> > -----Original Message-----
> > >> >> >> >> > From: Cheng [mailto:zhoucheng2008@gmail.com]
> > >> >> >> >> > Sent: Sunday, February 05, 2012 7:56 AM
> > >> >> >> >> > To: java-user@lucene.apache.org
> > >> >> >> >> > Subject: Configure writer to write to FSDirectory?
> > >> >> >> >> >
> > >> >> >> >> > Hi,
> > >> >> >> >> >
> > >> >> >> >> > I build an RAMDirectory on a FSDirectory,
and would like
> the
> > >> writer
> > >> >> >> >> associated
> > >> >> >> >> > with the RAMDirectory to periodically write
to hard drive.
> > >> >> >> >> >
> > >> >> >> >> > Is this achievable?
> > >> >> >> >> >
> > >> >> >> >> > Thanks.
> > >> >> >> >>
> > >> >> >> >>
> > >> >> >> >>
> > >> ---------------------------------------------------------------------
> > >> >> >> >> To unsubscribe, e-mail:
> java-user-unsubscribe@lucene.apache.org
> > >> >> >> >> For additional commands, e-mail:
> > >> java-user-help@lucene.apache.org
> > >> >> >> >>
> > >> >> >> >>
> > >> >> >>
> > >> >> >>
> > >> ---------------------------------------------------------------------
> > >> >> >> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> > >> >> >> For additional commands, e-mail:
> java-user-help@lucene.apache.org
> > >> >> >>
> > >> >> >>
> > >> >>
> > >> >>
> ---------------------------------------------------------------------
> > >> >> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> > >> >> For additional commands, e-mail: java-user-help@lucene.apache.org
> > >> >>
> > >> >>
> > >>
> > >> ---------------------------------------------------------------------
> > >> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> > >> For additional commands, e-mail: java-user-help@lucene.apache.org
> > >>
> > >>
> > >
>
>
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