[jboss-jira] [JBoss JIRA] Updated: (JGRP-659) Merge and UNICAST sequencing problem

Tue Mar 25 13:13:42 EDT 2008

     [ http://jira.jboss.com/jira/browse/JGRP-659?page=all ]

Troy Schulz updated JGRP-659:
-----------------------------

    Attachment: ConcurrentMemberTest.java

This is a JUnit test that starts multiple members concurrently, and can be used to demonstrate this issue.  It does not fail 100% of the time, but does fail 50+% of the time.  The failure usually occurs when multiple subgroups are created initially.

> Merge and UNICAST sequencing problem
> ------------------------------------
>
>                 Key: JGRP-659
>                 URL: http://jira.jboss.com/jira/browse/JGRP-659
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 2.6, 2.4, 2.5
>            Reporter: Vladimir Blagojevic
>         Assigned To: Bela Ban
>             Fix For: 2.7
>
>         Attachments: ConcurrentMemberTest.java
>
>
> The problem is related to trashing of connection table in UNICAST during merge. Consider following scenario:
> There are 4 nodes in a cluster A,B,C, and D. After network split we have two islands A,B and C,D. When the network healing starts eventually MergeView gets installed in both islands. MergeView installation causes trashing of UNICAST connection table [1].
> However if we have a scenario where MergeView gets installed in A,B island at time T and it gets installed in island C,D at time T+N msec and a node from island A,B sends a unicast message in this N msec time window then we'll run into problems with unicast sequencing at C and D. Why? Because next message coming from island A,B into C,D will be will with sequence number > 1 and sequencing in UNICAST of C,D after connection trashing (from merge) expects starting sequence of 1. This causes UNICAST in C and/or D to wait forever for missing messages. Final outcome is thus that no more unicast message coming from A and/or B will ever be delivered at C and/or D!
> [1]http://jira.jboss.com/jira/browse/JGRP-348

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