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Posted to dev@lucene.apache.org by "Ethan Tao (JIRA)" <ji...@apache.org> on 2012/05/24 01:51:40 UTC
[jira] [Created] (SOLR-3484) LogUpdateProcessor throws
ConcurrentModificationException under multi-threading calls
Ethan Tao created SOLR-3484:
-------------------------------
Summary: LogUpdateProcessor throws ConcurrentModificationException under multi-threading calls
Key: SOLR-3484
URL: https://issues.apache.org/jira/browse/SOLR-3484
Project: Solr
Issue Type: Bug
Components: update
Affects Versions: 4.0
Environment: linux
Reporter: Ethan Tao
Using the LogUpdateProcessor in a singleton chain for concurrent processing throws exception. The issue has been reported in SOLR-2694 (closed), and an unoffical patch can be found in related bug-id SOLR-2804 patch dated 1/1/12.
If the patch won't become official for LogUpdateProcessor, suggested to have new class "ConcurrentLogUpdateProcessorFactory" to address the thread safe issue.
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[jira] [Commented] (SOLR-3484) LogUpdateProcessor throws
ConcurrentModificationException under multi-threading calls
Posted by "Aaron Simmons (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/SOLR-3484?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13290348#comment-13290348 ]
Aaron Simmons commented on SOLR-3484:
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I have read the related tickets [SOLR-2694, SOLR-2804, SOLR-2694] .. and I still think this is a bug in LogUpdateProcessor, or maybe SolrWriter's usage of LogUpdateProcessor?!?
My environment is a Solr Cloud instance with 21 nodes. (solr-spec-version=4.0.0.2012.03.14.16.31.07)
When we kicked off a regular full-import of a data source (~5 million rows) .. it starts off fine, but then the import crashes. Looking over the log files, I find this on one of the nodes:
INFO: [core_NAME_slice11_shard1] webapp=/solr path=/select params={command=status&qt=/dataimport} status=0 QTime=1
Jun 5, 2012 7:24:22 PM org.apache.solr.handler.dataimport.SolrWriter upload
WARNING: Error creating document : SolrInputDocument[{ --LOTS OF DATA HERE-- }]
java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
at java.util.HashMap$KeyIterator.next(HashMap.java:828)
at org.apache.solr.common.util.IteratorChain.next(IteratorChain.hava:73)
at org.apache.solr.common.params.ModifiableSolrParams.add(ModifiableSolrParams.java:116)
at org.apache.solr.common.params.ModifiableSolrParams.<init>(ModifiableSolrParams.java:56)
at org.apache.solr.update.processor.DistributedUpdateProcessor.processAdd(DistributedUpdateProcessor.java:268)
at org.apache.solr.update.processor.LogUpdateProcessor.processAdd(LogUpdateProcessor.java:115)
at org.apache.solr.handler.dataimport.SolrWriter.upload(SolrWriter.java:70)
at org.apache.solr.handler.dataimport.DataImportHandler$1.upload(DataImportHandler.java:289)
at org.apache.solr.handler.dataimport.DocBuilder.buildDocument(DocBuilder.java:722)
at org.apache.solr.handler.dataimport.DocBuilder.buildDocument(DocBuilder.java:618)
at org.apache.solr.handler.dataimport.DocBuilder.doFullDump(DocBuilder.java:324)
at org.apache.solr.handler.dataimport.DocBuilder.execute(DocBuilder.java:222)
at org.apache.solr.handler.dataimport.DataImporter.doFullImport(DataImporter.java:382)
at org.apache.solr.handler.dataimport.DataImporter.runCmd(DataImporter.java:450)
at org.apache.solr.handler.dataimport.DataImporter$1.run(DataImporter.java:431)
We are using the 'out of the box' DataImportHandler, connecting to a SQL Server, etc. This seems like a real issue/bug that in org.apache.solr.update.processor.LogUpdateProcessor.
I saw the patch from SOLR-2804 on 1/1/2012 ... and this seems like a valid fix. But some people made comments and indicated it was not a valid fix, perhaps communicating that it's not a real problem? And SOLR-2804 was closed with "Won't Fix" ... and this bug report is marked as "Not a Problem".
I see this as a very real problem .. but maybe I'm not understanding something. Thoughts anyone?
> LogUpdateProcessor throws ConcurrentModificationException under multi-threading calls
> --------------------------------------------------------------------------------------
>
> Key: SOLR-3484
> URL: https://issues.apache.org/jira/browse/SOLR-3484
> Project: Solr
> Issue Type: Bug
> Components: update
> Affects Versions: 4.0
> Environment: linux
> Reporter: Ethan Tao
>
> Using the LogUpdateProcessor in a singleton chain for concurrent processing throws exception. The issue has been reported in SOLR-2694 (closed), and an unoffical patch can be found in related bug-id SOLR-2804 patch dated 1/1/12.
> If the patch won't become official for LogUpdateProcessor, suggested to have new class "ConcurrentLogUpdateProcessorFactory" to address the thread safe issue.
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[jira] [Resolved] (SOLR-3484) LogUpdateProcessor throws
ConcurrentModificationException under multi-threading calls
Posted by "Hoss Man (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/SOLR-3484?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Hoss Man resolved SOLR-3484.
----------------------------
Resolution: Not A Problem
See comments in SOLR-2694, particularly "Mikhail Khludnev added a comment - 24/May/12 07:15" (the author of hte patch in question) in direct response to comment from creator of this issue.
All of the UpdateProcessor Factories are thread safe -- but *NONE* of the UpdateRequestProcessor classes returned by those factories are thread safe. UpdateRequestProcessors are designed to be used in the context of a single Solr request (hence the reason you need a SolrQueryRequest/SolrQueryResponse to get an instance). If code interacting with an UpdateRequestProcessor is multi-threaded, then _that_ client code needs to synchronize it's use of the UpdateRequestProcessor.
(This was the fundamental problem in SOLR-2804: multi-threaded DIH code was not using the UpdateRequestProcessor in a thread-safe manner).
Adding a "ConcurrentLogUpdateRequestProcessor" will not magically make it safe for multi-threaded code to call methods on an UpdateRequestProcessor chain -- because any of the other UpdateRequestProcessors in that chain are also likley to break from concurrent usage by multiple threads.
If you have custom code that uses UpdateRequestProcessors in a way that you believe is valid, and you still see a bug, then you need to provide a test case demonstrating your usage and the bug it produces -- based on comments posted here and in SOLR-2694 it seems like the usage being described is not valid, because it assumes any and all UpdateRequestProcessors are stateless and multi-thread-safe, which is not true. trivial example: RunUpdateProcessorFactory maintains un-synchronized state about uncommited changes for dealing with the transaction log.
> LogUpdateProcessor throws ConcurrentModificationException under multi-threading calls
> --------------------------------------------------------------------------------------
>
> Key: SOLR-3484
> URL: https://issues.apache.org/jira/browse/SOLR-3484
> Project: Solr
> Issue Type: Bug
> Components: update
> Affects Versions: 4.0
> Environment: linux
> Reporter: Ethan Tao
>
> Using the LogUpdateProcessor in a singleton chain for concurrent processing throws exception. The issue has been reported in SOLR-2694 (closed), and an unoffical patch can be found in related bug-id SOLR-2804 patch dated 1/1/12.
> If the patch won't become official for LogUpdateProcessor, suggested to have new class "ConcurrentLogUpdateProcessorFactory" to address the thread safe issue.
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[jira] [Commented] (SOLR-3484) LogUpdateProcessor throws
ConcurrentModificationException under multi-threading calls
Posted by "Mikhail Khludnev (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/SOLR-3484?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13290380#comment-13290380 ]
Mikhail Khludnev commented on SOLR-3484:
----------------------------------------
[~aaronsimmons], particularly your problem caused by using threads in DIH. DIH shares single updateProcessorsChain among threads, that's wrong, those chains are single thread objects, ever!
Beside of this minor issue (which can be solved by log configuration), it's worth to mention that DIH worked incorrectly in multiple threads - I suppose you have more significant problem with incorrect data import. AFAIK fixed version is exist in 3.6.x branch, and threads were removed in 4.0 aka trunk.
[~hossman_lucene@fucit.org] I'm sorry for my misguiding SOLR-2804 patches. I removed them.
> LogUpdateProcessor throws ConcurrentModificationException under multi-threading calls
> --------------------------------------------------------------------------------------
>
> Key: SOLR-3484
> URL: https://issues.apache.org/jira/browse/SOLR-3484
> Project: Solr
> Issue Type: Bug
> Components: update
> Affects Versions: 4.0
> Environment: linux
> Reporter: Ethan Tao
>
> Using the LogUpdateProcessor in a singleton chain for concurrent processing throws exception. The issue has been reported in SOLR-2694 (closed), and an unoffical patch can be found in related bug-id SOLR-2804 patch dated 1/1/12.
> If the patch won't become official for LogUpdateProcessor, suggested to have new class "ConcurrentLogUpdateProcessorFactory" to address the thread safe issue.
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