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Date: Wed, 1 Jun 2016 15:10:20 +0530
Message-ID: <CAGW2whRYzRgGwHtzvgWT4jo_E30SwSf89kE=QeiL3nVRpUZG0A@mail.gmail.com>
Subject: Re: IndexReaderClosedException...
From: Ravikumar Govindarajan <ravikumar.govindarajan@gmail.com>
To: "blur-user@incubator.apache.org" <blur-user@incubator.apache.org>
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archived-at: Wed, 01 Jun 2016 09:40:26 -0000

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>
> In newer versions of the code there are multiple streams involved.  One for
> each open file handle plus if a sequential read is detected a new stream is
> created for the instance for better performance


Great. We just patched up our Blur version with this code.

While I was digging at the reader-closed issue, was quite surprised to
observe the following behavior

   - Issue a commit
   - Lucene opens a new reader via IndexWriter. (Doesn't re-use our already
   opened DirectoryReader)
   - Processes all updates/deletes/merges
   - Closes the new reader
   - Complete commit

For a big index & lots of commits, opening a new-reader for every commit is
prohibitively expensive.


Here is the JIRA for it...
https://issues.apache.org/jira/browse/LUCENE-2297

All we need to do is just set "readerPooling=true" in IndexWriterConfig
class

Please do explore this option when you find time.

--
Ravi


On Tue, May 24, 2016 at 7:48 PM, Aaron McCurry <amccurry@gmail.com> wrote:

> On Tue, May 24, 2016 at 6:06 AM, Ravikumar Govindarajan <
> ravikumar.govindarajan@gmail.com> wrote:
>
> > We have solved it temporarily by using a KeepLastTwoCommits del policy.
> We
> > don't get these exceptions now!!!
> >
>
> Great!
>
>
> >
> > Btw, I see that pread calls in FSDataInputStream.java are synchronized.
> Is
> > it possible that merge DFS read calls could potentially block search DFS
> > read calls?
> >
>
> Yes.
>
>
> >
> > Would it be a good idea to have 2 DFSInputStreams for every file, one for
> > merge & another for search?
> >
>
> In newer versions of the code there are multiple streams involved.  One for
> each open file handle plus if a sequential read is detected a new stream is
> created for the instance for better performance.  Checkout the
> HdfsDirectory class.
>
> Aaron
>
>
> >
> > On Tue, May 10, 2016 at 7:43 PM, Ravikumar Govindarajan <
> > ravikumar.govindarajan@gmail.com> wrote:
> >
> > > Sorry, I mis-understood the code.
> > > I see that it has 2 locks IndexRefreshWriteLock &
> IndexRefreshReadLock.
> > > They look to be separate
> > >
> > > On Tue, May 10, 2016 at 7:16 PM, Ravikumar Govindarajan <
> > > ravikumar.govindarajan@gmail.com> wrote:
> > >
> > >> Thanks a lot Aaron.
> > >>
> > >> I guess we took a commit of 0.2.2 that doesn't have the
> > >> IndexRefreshWriteLock (IRWL). It looks like it co-ordinates between
> > >> searches & incoming mutation commits. If so, then it will likely solve
> > the
> > >> first issue for us (AlreadyClosedException)
> > >>
> > >>
> > >> Can you recollect if that was the reason IRWL was introduced?
> > >>
> > >> On Tue, May 10, 2016 at 6:40 PM, Aaron McCurry <amccurry@gmail.com>
> > >> wrote:
> > >>
> > >>> On Tue, May 10, 2016 at 2:30 AM, Ravikumar Govindarajan <
> > >>> ravikumar.govindarajan@gmail.com> wrote:
> > >>>
> > >>> > Actually there are 2 issues...
> > >>> >
> > >>> > 1. IndexReaderClosedException
> > >>> > 2. HDFS Stream Closed
> > >>> >
> > >>>
> > >>> Likely when the index is closed it closes the underlying indexinputs
> as
> > >>> well causing the HDFS Stream closed exception.
> > >>>
> > >>>
> > >>> >
> > >>> > Merge completion results in File Deletion & ultimately HDFS Stream
> > >>> Closed
> > >>> > during Search....
> > >>> >
> > >>> > I use IndexFileDeleter with KeepOnlyLastCommitDeletionPolicy. This
> > >>> blindly
> > >>> > deletes the file, without bothering to cross-check
> > >>> IndexReader.RefCount >
> > >>> > 0.
> > >>> >
> > >>>
> > >>> Hmm.  You can see here:
> > >>>
> > >>>
> > >>>
> >
> https://github.com/apache/incubator-blur/blob/release-0.2.2-incubating/blur-core/src/main/java/org/apache/blur/manager/writer/BlurIndexSimpleWriter.java#L303
> > >>>
> > >>> That once the new index is available it is swapped into the index ref
> > >>> object and the old one is sent to the index closer.  Once the ref to
> > the
> > >>> index are low enough it closes the index.  Or at least it should.
> > >>>
> > >>> I will continue looking into the problem but I don't have a solution
> > for
> > >>> you yet.
> > >>>
> > >>> Aaron
> > >>>
> > >>>
> > >>>
> > >>> >
> > >>> >
> > >>> > *Exception(message:Unknown error during rewrite,
> > >>> > stackTraceStr:java.io.IOException: Stream closed*
> > >>> > at
> > >>> org.apache.hadoop.hdfs.DFSInputStream.pread(DFSInputStream.java:1385)
> > >>> > at
> > org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1374)
> > >>> > at
> > >>>
> org.apache.hadoop.fs.FSDataInputStream.read(FSDataInputStream.java:89)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.store.hdfs.HdfsIndexInput.readInternal(HdfsIndexInput.java:62)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.store.buffer.ReusedBufferedIndexInput.readBytes(ReusedBufferedIndexInput.java:167)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.store.buffer.ReusedBufferedIndexInput.readBytes(ReusedBufferedIndexInput.java:122)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.store.hdfs.MmapCacheIndexInput.readAndcache(MmapCacheIndexInput.java:24)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.store.blockcache_v2.CacheIndexInput.fillNormally(CacheIndexInput.java:354)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.store.blockcache_v2.CacheIndexInput.fill(CacheIndexInput.java:379)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.store.blockcache_v2.CacheIndexInput.tryToFill(CacheIndexInput.java:297)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.store.blockcache_v2.CacheIndexInput.readByte(CacheIndexInput.java:151)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.lucene.warmup.TraceableIndexInput.readByte(TraceableIndexInput.java:62)
> > >>> > at org.apache.lucene.store.DataInput.readVInt(DataInput.java:108)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.lucene.codecs.BlockTreeTermsReader$FieldReader$SegmentTermsEnum$Frame.loadBlock(BlockTreeTermsReader.java:2366)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.lucene.codecs.BlockTreeTermsReader$FieldReader$SegmentTermsEnum.seekCeil(BlockTreeTermsReader.java:1949)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.blur.index.ExitableReader$ExitableTermsEnum.seekCeil(ExitableReader.java:250)
> > >>> > at
> > >>> >
> > >>>
> >
> org.apache.lucene.index.FilteredTermsEnum.next(FilteredTermsEnum.java:225)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.lucene.search.TermCollectingRewrite.collectTerms(TermCollectingRewrite.java:78)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.lucene.search.ConstantScoreAutoRewrite.rewrite(ConstantScoreAutoRewrite.java:95)
> > >>> > at
> > >>> >
> > >>> >
> > >>>
> >
> org.apache.lucene.search.MultiTermQuery$ConstantScoreAutoRewrite.rewrite(MultiTermQuery.java:220)
> > >>> > at
> > >>>
> > org.apache.lucene.search.MultiTermQuery.rewrite(MultiTermQuery.java:288)
> > >>> > at
> > org.apache.lucene.search.BooleanQuery.rewrite(BooleanQuery.java:412)
> > >>> > at
> > org.apache.lucene.search.BooleanQuery.rewrite(BooleanQuery.java:412)
> > >>> > at
> > org.apache.lucene.search.BooleanQuery.rewrite(BooleanQuery.java:412)
> > >>> > at
> > >>> >
> > >>> > On Mon, May 9, 2016 at 4:42 PM, Ravikumar Govindarajan <
> > >>> > ravikumar.govindarajan@gmail.com> wrote:
> > >>> >
> > >>> > > One extra info we gleaned from the logs...
> > >>> > >
> > >>> > > 1. Merge Starts & is about to complete
> > >>> > > 2. Searcher is opened
> > >>> > > 3. Merge Completes
> > >>> > > 4. Ref-count drops to 0 in IndexReader
> > >>> > > 5. IndexReader closed while Searcher is still open
> > >>> > >
> > >>> > > This seems to be the main pattern for causing the Exception
> > >>> > >
> > >>> > > --
> > >>> > > Ravi
> > >>> > >
> > >>> > > On Mon, May 9, 2016 at 3:08 PM, Ravikumar Govindarajan <
> > >>> > > ravikumar.govindarajan@gmail.com> wrote:
> > >>> > >
> > >>> > >> Thanks Aaron...
> > >>> > >>
> > >>> > >> Just a quick question. Lucene itself has ref-counting to close
> > it's
> > >>> > >> readers no? Or Blur has it's own logic to handle it?
> > >>> > >>
> > >>> > >> --
> > >>> > >> Ravi
> > >>> > >>
> > >>> > >> On Fri, May 6, 2016 at 7:56 PM, Aaron McCurry <
> amccurry@gmail.com
> > >
> > >>> > wrote:
> > >>> > >>
> > >>> > >>> Likely yes.  If have a few minutes this weekend I can look
> > through
> > >>> that
> > >>> > >>> version and see if I can point you in the right direction.
> > >>> > >>>
> > >>> > >>> On Fri, May 6, 2016 at 8:46 AM, Ravikumar Govindarajan <
> > >>> > >>> ravikumar.govindarajan@gmail.com> wrote:
> > >>> > >>>
> > >>> > >>> > Sometimes during an ongoing search we receive an
> > >>> > >>> > IndexReaderClosedException...
> > >>> > >>> >
> > >>> > >>> > We are on an older version of Blur (0.2.2). Has this been
> fixed
> > >>> in
> > >>> > >>> newer
> > >>> > >>> > versions or we have been using it wrongly?
> > >>> > >>> >
> > >>> > >>> >
> *stackTraceStr:org.apache.lucene.store.AlreadyClosedException:
> > >>> this
> > >>> > >>> > IndexReader cannot be used anymore as one of its child
> readers
> > >>> was
> > >>> > >>> closed*
> > >>> > >>> > at
> > >>> >
> org.apache.lucene.index.IndexReader.ensureOpen(IndexReader.java:257)
> > >>> > >>> > at
> > >>> > >>> >
> > >>> > >>> >
> > >>> > >>>
> > >>> >
> > >>>
> >
> org.apache.lucene.index.FilterAtomicReader.fields(FilterAtomicReader.java:380)
> > >>> > >>> > at
> > >>> > >>> >
> > >>> > >>> >
> > >>> > >>>
> > >>> >
> > >>>
> >
> org.apache.blur.index.ExitableReader$ExitableFilterAtomicReader.fields(ExitableReader.java:81)
> > >>> > >>> > at
> > >>> > >>> >
> > >>> > >>> >
> > >>> > >>>
> > >>> >
> > >>>
> >
> org.apache.lucene.search.TermCollectingRewrite.collectTerms(TermCollectingRewrite.java:52)
> > >>> > >>> > at
> > >>> > >>> >
> > >>> > >>> >
> > >>> > >>>
> > >>> >
> > >>>
> >
> org.apache.lucene.search.ConstantScoreAutoRewrite.rewrite(ConstantScoreAutoRewrite.java:95)
> > >>> > >>> > at
> > >>> > >>> >
> > >>> > >>> >
> > >>> > >>>
> > >>> >
> > >>>
> >
> org.apache.lucene.search.MultiTermQuery$ConstantScoreAutoRewrite.rewrite(MultiTermQuery.java:220)
> > >>> > >>> > at
> > >>> > >>>
> > >>> >
> > >>>
> > org.apache.lucene.search.MultiTermQuery.rewrite(MultiTermQuery.java:288)
> > >>> > >>> > at
> > >>> >
> org.apache.lucene.search.BooleanQuery.rewrite(BooleanQuery.java:412)
> > >>> > >>> >
> > >>> > >>>
> > >>> > >>
> > >>> > >>
> > >>> > >
> > >>> >
> > >>>
> > >>
> > >>
> > >
> >
>

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