[jboss-jira] [JBoss JIRA] Commented: (JGRP-1029) Discovery: return_entire_cache ends up with incorrect list of views

[Bela Ban (JIRA)]

    [ https://jira.jboss.org/jira/browse/JGRP-1029?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12482822#action_12482822 ] 

Bela Ban commented on JGRP-1029:
--------------------------------

To reproduce:
- Add <DISCARD use_gui="true"/> to tcp.xml
- Start 3 instances
- Have each instance start dropping messages
- We now have 3 singleton clusters
- Now have the 3 instances accept messages again
--> Because every member thinks a different member is the merge leader, a merge will not happen !

> Discovery: return_entire_cache ends up with incorrect list of views
> -------------------------------------------------------------------
>
>                 Key: JGRP-1029
>                 URL: https://jira.jboss.org/jira/browse/JGRP-1029
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 2.8
>
>
> When return_entire_cache is set to true (default in TCPPING), then we can have the following scenario:
> - A, B and C
> - A's cache: 
>     - A: 123 / VA (View A)
>     - B: 456 / VA
>     - C: 777 / VA
> - B's cache:
>     - A: 123 / VB
>     - B: 456 / VB
>     - C: 777 / VB
> - C's cache:
>     - A: 123 / VC
>     - B: 456 / VC
>     - C: 777 / VC
> When we now have a discovery request, A, B and C return their entire cache. Depending on the order in which we receive the discovery responses, and the value of num_initial_rsps, the views can be inconsistent, e.g. if we get the following responses:
> - B: A: 123 / VB
> - C: B: 456 / VC
> - A: A: 123 / VA
> , then our views are A -> VB and B -> VC  ! A's 2nd discovery response is simply discarded, as we already have an entry for A !
> This leads to merges not happening

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