[jboss-jira] [JBoss JIRA] Commented: (JGRP-505) UNICAST: sequence numbering after merge leads to messages never being delivered

[Bela Ban (JIRA)]

    [ http://jira.jboss.com/jira/browse/JGRP-505?page=comments#action_12364386 ] 
            
Bela Ban commented on JGRP-505:
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Okay, I now think this is a race issue between the merge view (multicast) and the reception of the subsequent message (unicast). Not sure how to solve this as unicast and multicasts are not related ordering wise.
I'm looking further into this

> UNICAST: sequence numbering after merge leads to messages never being delivered
> -------------------------------------------------------------------------------
>
>                 Key: JGRP-505
>                 URL: http://jira.jboss.com/jira/browse/JGRP-505
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 2.4.1
>            Reporter: Vladimir Blagojevic
>         Assigned To: Vladimir Blagojevic
>             Fix For: 2.5
>
>
> During refactoring of TUNNEL to use TP I ran MultiplexerMergeTest very often. This test basically consists of two members A and B that are exchanging message through GossipRouter. When GossipRouter is killed members form their own subgroups that are subsequently merged once router starts again. 
> I noticed that on very rare occasions (1 in 20 test runs) one of the members (say A) stops passing up unicast messages from B above UNICAST protocol. More detailed logging and inquiry at UNICAST revealed that upon merge A stops passing up messages from B and keeps adding messages from B seq>1 into B's window but does not pass up messages further since message seq B1 is missing. After further investigation I concluded that message B1 must have been delivered to A prior to MergeView. MergeView wiped clean all windows and added next sequence B2 to appropriate window. 
> I am not sure if this is only applicable to Multiplexer setup. The issue is hard to reproduce. I will see if it is possible to make a unit test to reproduce it.

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