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https://issues.apache.org/jira/browse/SOLR-6530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14139170#comment-14139170
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Alan Woodward commented on SOLR-6530:
-------------------------------------

Think I just came across another version of this:

1. A is leader, and is distributing docs to B
2. A gets a large GC pause, during which B takes over as leader
3. A wakes up again, continues to send docs from DistributedUpdateProcessor, 
but now gets errors in response because B is refusing the updates (as they're 
marked as FROMLEADER, and B is now the leader)
4. In DUP.doFinish(), A finds that it has a bunch of errors from B, and so it 
attempts to put B into recovery, with the same result as point 4 in the issue 
description

> Commits under network partition can put any node in down state by any node
> --------------------------------------------------------------------------
>
>                 Key: SOLR-6530
>                 URL: https://issues.apache.org/jira/browse/SOLR-6530
>             Project: Solr
>          Issue Type: Bug
>          Components: SolrCloud
>            Reporter: Shalin Shekhar Mangar
>            Priority: Critical
>             Fix For: 5.0, 6.0
>
>         Attachments: SOLR-6530.patch, SOLR-6530.patch
>
>
> Commits are executed by any node in SolrCloud i.e. they're not routed via the 
> leader like other updates. 
> # Suppose there's 1 collection, 1 shard, 2 replicas (A and B) and A is the 
> leader
> # Suppose a commit request is made to node B during a time where B cannot 
> talk to A due to a partition for any reason (failing switch, heavy GC, 
> whatever)
> # B fails to distribute the commit to A (times out) and asks A to recover
> # This was okay earlier because a leader just ignores recovery requests but 
> with leader initiated recovery code, B puts A in the "down" state and A can 
> never get out of that state.
> tl;dr; During network partitions, if enough commit/optimize requests are sent 
> to the cluster, all the nodes in the cluster will eventually be marked as 
> "down".



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