[infinispan-issues] [JBoss JIRA] (ISPN-6425) FileNotFoundException with async indexing backend

Tue Apr 19 10:49:00 EDT 2016

    [ https://issues.jboss.org/browse/ISPN-6425?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13193851#comment-13193851 ] 

Gustavo Fernandes commented on ISPN-6425:
-----------------------------------------

Right, let's first agree on the various {{async}} involved:

1. {{async cache store}}: writes to the cache store are done in a separate thread that the one doing the {{cache.put}}. Applies to all regular cache stores, not directly related to indexing or lucene. This has been around since eariler versions of Infinispan (5+)
2. {{async indexing backend}}: lucene indexing are done separately from the {{cache.put}}, this does not need to involve a cache store, and could be configured to all indexing backends: filesystem, ram and infinispan directory. This has been available since Infinispan 6, but on Infinispan 7 it's performance increased drastically
3. {{write_metadata_async}}: this is a experimental indexing config that applies only when using indexes stored in Infinispan. Infinispan based lucene indexes are composed of 3 caches: Data, Metadada and Lock. This config applies only to the metadata cache writes. This is a config from Infinispan 7 onwards

Your case is related to 1 while this JIRA fixes 3, so I'd say your Infinispan version is not affected by this issue.

Regarding your {{FileNotFoundException}} exception, I'd strong recommend you to consider upgrading to latest Infinispan, as it has several fixes and huge performance improvements for the indexing and queries in general.

> FileNotFoundException with async indexing backend
> -------------------------------------------------
>
>                 Key: ISPN-6425
>                 URL: https://issues.jboss.org/browse/ISPN-6425
>             Project: Infinispan
>          Issue Type: Bug
>          Components: Embedded Querying, Lucene Directory
>    Affects Versions: 8.2.0.Final
>            Reporter: Gustavo Fernandes
>            Assignee: Gustavo Fernandes
>             Fix For: 8.2.1.Final, 9.0.0.Alpha1, 9.0.0.Final
>
>
> The Infinispan directory defaults to {{write_metadata_async=true}} when the indexing backend is configured as async, i.e. {{default.worker.execution}} is {{true}}.
> The {{write_metadata_async=true}} will use {{cache.putAsync}} to write the index file metadata, while still deleting and creating files syncronously. This can lead to 
> a stale metadata causing FileNotFoundExceptions when executing queries:
> Suppose a lucene directory contains files \[segments_4, _4.si\]. During normal regime, apart from the user thread, there could be other 2 threads that could be changing the index, the periodic commit thread (since backend is async) and the async deletion of files. 
> The following race can happen:
> ||Time||Thread||work type||work||
> |T1|Hibernate Search: Commit Scheduler for index| SYNC | write files segments_5 and _5.si to the index
> |T2|Hibernate Search: Commit Scheduler for index| ASYNC | write the new file list containing \[segments_4, _4.si, segments_5,_5.si\] 
> |T3|Hibernate Search: Commit Scheduler for index| ASYNC | enqueue a deletion task for files segments_4 and _4.si
> |T4|Hibernate Search: async deletion of index| SYNC | dequeue deletion task for files segments_4 and _4.si
> |T5|Hibernate Search: async deletion of index| SYNC | delete files segments_4 and _4.si from the index
> |T6|Hibernate Search: async deletion of index| ASYNC | write the new file list containing \[segments_5,_5.si\]
> |T7|User-thread| |open index reader, file list is \[segments_4, _4.si\], highest segment number is 4 (file list is not updated yet)
> |T8|User-thread| |open segments_4
> |T9|User-thread| |FileNotFoundException!
> |T10|remote-thread-User| | new file list received \[segments_4, _4.si, segments_5,_5.si\]
> |T11|remote-thread-User| | new file list received \[segments_5,_5.si\]
> This race can be observed in {{MassIndexerAsyncBackendTest#testMassIndexOnAsync}} that fails intermittently with the exception:
> {noformat}
> Caused by: java.io.FileNotFoundException: Error loading metadata for index file: M|segments_4|commonIndex|-1
> 	at org.infinispan.lucene.impl.DirectoryImplementor.openInput(DirectoryImplementor.java:138) ~[infinispan-lucene-directory-9.0.0-SNAPSHOT.jar:9.0.0-SNAPSHOT]
> 	at org.infinispan.lucene.impl.DirectoryLucene.openInput(DirectoryLucene.java:102) ~[infinispan-lucene-directory-9.0.0-SNAPSHOT.jar:9.0.0-SNAPSHOT]
> 	at org.apache.lucene.store.Directory.openChecksumInput(Directory.java:109) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:294) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.SegmentInfos$1.doBody(SegmentInfos.java:493) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.SegmentInfos$1.doBody(SegmentInfos.java:490) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:731) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:683) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.SegmentInfos.readLatestCommit(SegmentInfos.java:490) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.StandardDirectoryReader.isCurrent(StandardDirectoryReader.java:344) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.StandardDirectoryReader.doOpenNoWriter(StandardDirectoryReader.java:300) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.StandardDirectoryReader.doOpenIfChanged(StandardDirectoryReader.java:263) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> 	at org.apache.lucene.index.StandardDirectoryReader.doOpenIfChanged(StandardDirectoryReader.java:251) ~[lucene-core-5.5.0.jar:5.5.0 2a228b3920a07f930f7afb6a42d0d20e184a943c - mike - 2016-02-16 15:18:34]
> {noformat}
> We should not enable {{write_metadata_async=true}} for async backends. The file list is already {{DeltaAware}}, so writing should not pose a meaningfull overhead when done synchronously.

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