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

["Andrey Kudryavtsev (JIRA)" <ji...@apache.org>]

Andrey Kudryavtsev created SOLR-11459:
-----------------------------------------

             Summary: AddUpdateCommand#prevVersion is not cleared which may lead to problem for in-place updates for non existed
                 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)
            Reporter: Andrey Kudryavtsev


There is a story how I met this one. 
I have a 1_shard / *m*_replicas SolrCloud cluster 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 this:
* There are 100-500 updates for non-existed documents among regular updates (something that I have to deal with)
* Leader receives bunch of updates and executes this update 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]. [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 is not existed, 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 slave in DistributedUpdateProcessor. {{prevVersion}} wasn't cleared, so it may contain version from previous processed updates.
* Slaves checks it's own version on documents which is 0 (cause doc is not exists), 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 tried to get "correct" version from leader (no luck as well) 
* So update costs me *m* * 5 sec 

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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