lucene-java-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Michael McCandless <luc...@mikemccandless.com>
Subject Re: Configure writer to write to FSDirectory?
Date Mon, 06 Feb 2012 16:42:31 GMT
You shouldn't call IW.commit when using NRT; that's the point of NRT
(making changes visible w/o calling commit).

Only call commit when you require that all changes be durable (surive
OS / JVM crash, power loss, etc.) on disk.

Also, you can use NRTCachingDirectory which acts like RAMDirectory for
small flushed segments.

Mike McCandless

http://blog.mikemccandless.com

On Mon, Feb 6, 2012 at 10:45 AM, Cheng <zhoucheng2008@gmail.com> wrote:
> 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
>> > >>
>> > >>
>> > >
>>
>>
>> ---------------------------------------------------------------------
>> 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


Mime
View raw message