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From "Uwe Schindler" <...@thetaphi.de>
Subject RE: IndexWriter memory leak?
Date Thu, 08 Apr 2010 10:04:02 GMT
I already answered, that I will take care of this!

Uwe

-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe@thetaphi.de


> -----Original Message-----
> From: Shai Erera [mailto:serera@gmail.com]
> Sent: Thursday, April 08, 2010 12:00 PM
> To: java-user@lucene.apache.org
> Subject: Re: IndexWriter memory leak?
> 
> Yes, that's the trimBuffer version I was thinking about, only this guy
> created a reset(Reader, int) and does both ops (resetting + trim) in
> one
> method call. More convenient. Can you please open an issue to track
> that?
> People will have a chance to comment on whether we (Lucene) should
> handle
> that, or it should be a JFlex fix. Based on the number of replies this
> guy
> received (0 !), I doubt JFlex would consider it a problem. But we can
> do
> some small service to our users base by protecting against such
> problems.
> 
> And while you're opening the issue, if you want to take a stab at
> fixing it
> and post a patch, it'd be great :).
> 
> Shai
> 
> On Thu, Apr 8, 2010 at 12:51 PM, Ruben Laguna
> <ruben.laguna@gmail.com>wrote:
> 
> > I was investigating this a little further and in the JFlex mailing
> list I
> > found [1]
> >
> > I don't know much about flex / JFlex but it seems that this guy
> resets the
> > zzBuffer to 16384 or less when setting the input for the lexer
> >
> >
> > Quoted from  shef <shef31@ya...>
> >
> >
> > I set
> >
> > %buffer 0
> >
> > in the options section, and then added this method to the lexer:
> >
> >    /**
> >     * Set the input for the lexer. The size parameter really speeds
> things
> > up,
> >     * because by default, the lexer allocates an internal buffer of
> 16k.
> > For
> >     * most strings, this is unnecessarily large. If the size param is
> > 0 or greater
> >     * than 16k, then the buffer is set to 16k. If the size param is
> > smaller, then
> >     * the buf will be set to the exact size.
> >     * @param r the reader that provides the data
> >     * @param the size of the data in the reader.
> >     */
> >    public void reset(Reader r, int size) {
> >        if (size == 0 || size > 16384)
> >            size = 16384;
> >        zzBuffer = new char[size];
> >        yyreset(r);
> >    }
> >
> >
> > So maybe there is a way to trim the zzBuffer this way (?).
> >
> > BTW, I will try to find out which is the "big token" in my dataset
> this
> > afternoon. Thanks for the help.
> >
> > I actually workaround this memory problem for the time being by
> wrapping
> > the
> > IndexWriter in a class that periodically closes the IndexWriter and
> creates
> > a new one, allowing the old to be GCed, but I would be really good if
> > either
> > JFlex or Lucene can take care of this zzBuffer going berserk.
> >
> >
> > Again thanks for the quick response. /Rubén
> >
> >
> > [1]
> >
> >
> https://sourceforge.net/mailarchive/message.php?msg_id=444070.38422.qm@
> web38901.mail.mud.yahoo.com
> >
> > On Thu, Apr 8, 2010 at 11:32 AM, Shai Erera <serera@gmail.com> wrote:
> >
> > > If we could change the Flex file so that yyreset(Reader) would
> check the
> > > size of zzBuffer, we could trim it when it gets too big. But I
> don't
> > think
> > > we have such control when writing the flex syntax ... yyreset is
> > generated
> > > by JFlex and that's the only place I can think of to trim the
> buffer down
> > > when it exceeds a predefined threshold ....
> > >
> > > Maybe what we can do is create our own method which will be called
> by
> > > StandardTokenizer after yyreset is called, something like
> > > trimBufferIfTooBig(int threshold) which will reallocate zzBuffer if
> it
> > > exceeded the threshold. We can decide on a reasonable 64K threshold
> or
> > > something, or simply always cut back to 16 KB. As far as I
> understand,
> > that
> > > buffer should never grow that much. I.e. in zzRefill, which is the
> only
> > > place where the buffer gets resized, there is an attempt to first
> move
> > back
> > > characters that were already consumed and only then allocate a
> bigger
> > > buffer. Which means only if there is a token whose size is larger
> than
> > 16KB
> > > (!?), will this buffer get expanded.
> > >
> > > A trimBuffer method might not be that bad .. as a protective
> measure.
> > What
> > > do you think? Of course, JFlex can fix it on their own ... but
> until that
> > > happens ...
> > >
> > > Shai
> > >
> > > On Thu, Apr 8, 2010 at 10:35 AM, Uwe Schindler <uwe@thetaphi.de>
> wrote:
> > >
> > > > > I would like to identify also the problematic document I have
> 10000
> > so,
> > > > > what
> > > > > would be the best way of identifying the one that it making
> zzBuffer
> > to
> > > > > grow
> > > > > without control?
> > > >
> > > > Dont index your documents, but instead pass them directly to the
> > analyzer
> > > > and consume the tokenstream manually. Then visit
> > > TermAttribute.termLength()
> > > > for each Token.
> > > >
> > > >
> > > > -----------------------------------------------------------------
> ----
> > > > To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> > > > For additional commands, e-mail: java-user-help@lucene.apache.org
> > > >
> > > >
> > >
> >
> >
> >
> > --
> > /Rubén
> >


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