[jboss-jira] [JBoss JIRA] (JGRP-1910) MERGE3: Do not lose any members from view during a series of merges

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1910?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13049238#comment-13049238 ] 

Bela Ban commented on JGRP-1910:
--------------------------------

Added {{GMS.use_all_views_to_determine_merge_leaders}} (default=true) to define whether to select all view creators as potential merge leaders (true), or to select only view creators which are also the senders of view-ids (false). Default is true, so this is a slight change of behavior.
The change is that now we reduced the chances of parallel merges happening, but also slightly increased the chances of a merge leader not being accessible and merging having to wait until that coord is suspected and excluded.

> MERGE3: Do not lose any members from view during a series of merges
> -------------------------------------------------------------------
>
>                 Key: JGRP-1910
>                 URL: https://issues.jboss.org/browse/JGRP-1910
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Radim Vansa
>            Assignee: Bela Ban
>             Fix For: 3.6.3
>
>         Attachments: SplitMergeFailFastTest.java, SplitMergeTest.java
>
>
> When connection between nodes is re-established, MERGE3 should merge the cluster together. This often does not involve a single MergeView but a series of such events. The problematic property of this protocol is that some of those views can lack certain members, though these are reachable.
> This causes problem in Infinispan since the cache cannot be fully rebalanced before another merge arrives, and all owners of certain segment can be gradually removed (and added again) to the view, while this is not detected as partition but crashed nodes -> losing all owners means data loss.
> Removing members from view should be the role of FDx protocols, not MERGEx.



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