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From Ruben Laguna <ruben.lag...@gmail.com>
Subject Re: IndexWriter memory leak?
Date Thu, 08 Apr 2010 20:33:27 GMT
Yeah, I checked again and IndexWriter is holding references to the Reader,
I'm afraid.

 I opened bug report https://issues.apache.org/jira/browse/LUCENE-2387 to
track this down.

On Thu, Apr 8, 2010 at 2:50 PM, Ruben Laguna <ruben.laguna@gmail.com> wrote:

> I will double check in the afternoon the heapdump.hprof. But I think that
> *some* readers are indeed held by docWriter.threadStates[0].consumer.fieldHash[1].fields[xxxx],
> as shown in [1] (this heapdump contains only live objects).  The heapdump
> was taken after IndexWriter.commit() /IndexWriter.optimize() and all the
> Documents were already indexed and GCed (I will double check).
>
> So that would mean that the Reader is retained in memory by the following
> chaing of references,
>
> DocumentsWriter -> DocumentsWriterThreadState -> DocFieldProcessorPerThread
> -> DocFieldProcessorPerField -> Fieldable -> Field (fieldsData)
>
> I'll double check with Eclipse MAT as I said that this chain is actually
> made of hard references only (no SoftReferences,WeakReferences, etc). I will
> also double check also that there is no "live" Document that is referencing
> the Reader via the Field.
>
>
> [1] http://img.skitch.com/20100407-b86irkp7e4uif2wq1dd4t899qb.jpg
>
> On Thu, Apr 8, 2010 at 2:16 PM, Uwe Schindler <uwe@thetaphi.de> wrote:
>
>> Readers are not held. If you indexed the document and gced the document
>> instance they readers are gone.
>>
>> -----
>> Uwe Schindler
>> H.-H.-Meier-Allee 63, D-28213 Bremen
>> http://www.thetaphi.de
>> eMail: uwe@thetaphi.de
>>
>>
>> > -----Original Message-----
>> > From: Ruben Laguna [mailto:ruben.laguna@gmail.com]
>> > Sent: Thursday, April 08, 2010 1:28 PM
>> > To: java-user@lucene.apache.org
>> > Subject: Re: IndexWriter memory leak?
>> >
>> > Now that the zzBuffer issue is solved...
>> >
>> > what about the references to the Readers held by docWriter. Tika´s
>> > ParsingReaders are quite heavyweight so retaining those in memory
>> > unnecesarily is also a "hidden" memory leak. Should I open a bug report
>> > on
>> > that one?
>> >
>> > /Rubén
>> >
>> > On Thu, Apr 8, 2010 at 12:11 PM, Shai Erera <serera@gmail.com> wrote:
>> >
>> > > Guess we were replying at the same time :).
>> > >
>> > > On Thu, Apr 8, 2010 at 1:04 PM, Uwe Schindler <uwe@thetaphi.de>
>> > wrote:
>> > >
>> > > > 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
>> > > > > >
>> > > >
>> > > >
>> > > > -------------------------------------------------------------------
>> > --
>> > > > To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
>> > > > For additional commands, e-mail: java-user-help@lucene.apache.org
>> > > >
>> > > >
>> > >
>> >
>> >
>> >
>> > --
>> > /Rubén
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
>> For additional commands, e-mail: java-user-help@lucene.apache.org
>>
>>
>
>
> --
> /Rubén
>



-- 
/Rubén

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