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From Aaron McCurry <amccu...@gmail.com>
Subject Re: IndexReaderClosedException...
Date Tue, 07 Jun 2016 11:14:22 GMT
On Wed, Jun 1, 2016 at 5:40 AM, Ravikumar Govindarajan <
ravikumar.govindarajan@gmail.com> wrote:

> >
> > 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.
>

Interesting.  The current code in the trunk doesn't reopen the indexreader
form the writer.  It reuses the existing reader.


>
> --
> 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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