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From Shai Erera <ser...@gmail.com>
Subject Re: IndexWriter memory leak?
Date Thu, 08 Apr 2010 09:59:54 GMT
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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