[jira] [Commented] (SOLR-11459) AddUpdateCommand#prevVersion is not cleared which may lead to problem for in-place updates of non existed documents

["Mikhail Khludnev (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SOLR-11459?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16351869#comment-16351869 ] 

Mikhail Khludnev commented on SOLR-11459:
-----------------------------------------

Great investigation and the test, [~werder]. I'm going to commit [^SOLR-11459.patch] next week.

Note: rolling back one-liner fix fails well with  

{{ant test  -Dtestcase=TestInPlaceUpdatesDistrib -Dtests.seed=693C5C2078500204:553EDF06E26EA4D0 -Dtests.slow=true -Dtests.locale=ga -Dtests.timezone=US/Arizona -Dtests.asserts=true -Dtests.file.encoding=UTF-8}}

 

> AddUpdateCommand#prevVersion is not cleared which may lead to problem for in-place updates of non existed documents
> -------------------------------------------------------------------------------------------------------------------
>
>                 Key: SOLR-11459
>                 URL: https://issues.apache.org/jira/browse/SOLR-11459
>             Project: Solr
>          Issue Type: Bug
>      Security Level: Public(Default Security Level. Issues are Public) 
>          Components: SolrCloud
>    Affects Versions: 7.0
>            Reporter: Andrey Kudryavtsev
>            Assignee: Mikhail Khludnev
>            Priority: Minor
>         Attachments: SOLR-11459.patch
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> I have a 1_shard / *m*_replicas SolrCloud cluster with Solr 6.6.0 and run batches of 5 - 10k in-place updates from time to time. 
> Once I noticed that job "hangs" - it started and couldn't finish for a a while.
> Logs were full of messages like:
> {code} Missing update, on which current in-place update depends on, hasn't arrived. id=__, looking for version=___, last found version=0"  {code}
> {code} 
> Tried to fetch document ___ from the leader, but the leader says document has been deleted. Deleting the document here and skipping this update: Last found version: 0, was looking for: ___",24,0,"but the leader says document has been deleted. Deleting the document here and skipping this update: Last found version: 0
> {code}
> Further analysis shows that:
> * There are 100-500 updates for non-existed documents among other updates (something that I have to deal with)
> * Leader receives bunch of updates and executes this updates one by one. {{JavabinLoader}} which is used by processing documents reuses same instance of {{AddUpdateCommand}} for every update and just [clearing its state at the end|https://github.com/apache/lucene-solr/blob/e2521b2a8baabdaf43b92192588f51e042d21e97/solr/core/src/java/org/apache/solr/handler/loader/JavabinLoader.java#L99]. Field [AddUpdateCommand#prevVersion| https://github.com/apache/lucene-solr/blob/6396cb759f8c799f381b0730636fa412761030ce/solr/core/src/java/org/apache/solr/update/AddUpdateCommand.java#L76] is not cleared.   
> * In case of update is in-place update, but specified document does not exist, this update is processed as a regular atomic update (i.e. new doc is created), but {{prevVersion}} is used as a {{distrib.inplace.prevversion}} parameter in sequential calls to every slave in DistributedUpdateProcessor. {{prevVersion}} wasn't cleared, so it may contain version from previous processed update.
> * Slaves checks it's own version of documents which is 0 (cause doc does not exist), slave thinks that some updates were missed and spends 5 seconds in [DistributedUpdateProcessor#waitForDependentUpdates|https://github.com/apache/lucene-solr/blob/e2521b2a8baabdaf43b92192588f51e042d21e97/solr/core/src/java/org/apache/solr/handler/loader/JavabinLoader.java#L99] waiting for missed updates (no luck) and also tries to get "correct" version from leader (no luck as well) 
> * So update for non existed document costs *m* * 5 sec each
> I workarounded this by explicit check of doc existence, but it probably should be fixed.
> Obviously first guess is that  prevVersion should be cleared in {{AddUpdateCommand#clear}}, but have no clue how to test it.
> {code}
> +++ solr/core/src/java/org/apache/solr/update/AddUpdateCommand.java	(revision )
> @@ -78,6 +78,7 @@
>       updateTerm = null;
>       isLastDocInBatch = false;
>       version = 0;
> +     prevVersion = -1;
>     }
> {code}



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