> > I didn't fully understand the underlying Lucene reader, writer, > open, close semantics
I too don't know the correct behavior. Lucene code is incredibly hairy to follow... :) Have pinged lucene mailing list. Hope someone replies... On Tue, Jun 7, 2016 at 4:46 PM, Aaron McCurry <[email protected]> wrote: > On Wed, Jun 1, 2016 at 7:34 AM, Ravikumar Govindarajan < > [email protected]> wrote: > > > Just one more observation here... > > > > Even if readerPooling is set to true, lucene has 2 readers (One for > search > > & one updates/deletes) > > > > But the reader for updates/deletes is not opened/closed for every commit > > call which is the default behavior as of today. It is opened only once > > (During first update/delete call) > > > > I will take a closer look at the code for this one. Likely when I wrote > this code I didn't fully understand the underlying Lucene reader, writer, > open, close semantics. Thank you for pointing this out! > > Aaron > > > > > > On Wed, Jun 1, 2016 at 3:10 PM, Ravikumar Govindarajan < > > [email protected]> 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. > > > > > > -- > > > Ravi > > > > > > > > > > > > On Tue, May 24, 2016 at 7:48 PM, Aaron McCurry <[email protected]> > > wrote: > > > > > >> On Tue, May 24, 2016 at 6:06 AM, Ravikumar Govindarajan < > > >> [email protected]> 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 < > > >> > [email protected]> 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 < > > >> > > [email protected]> 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 < > [email protected] > > > > > >> > >> wrote: > > >> > >> > > >> > >>> On Tue, May 10, 2016 at 2:30 AM, Ravikumar Govindarajan < > > >> > >>> [email protected]> 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 < > > >> > >>> > [email protected]> 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 < > > >> > >>> > > [email protected]> 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 < > > >> [email protected] > > >> > > > > >> > >>> > 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 < > > >> > >>> > >>> [email protected]> 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) > > >> > >>> > >>> > > > >> > >>> > >>> > > >> > >>> > >> > > >> > >>> > >> > > >> > >>> > > > > >> > >>> > > > >> > >>> > > >> > >> > > >> > >> > > >> > > > > >> > > > >> > > > > > > > > >
