[jboss-jira] [JBoss JIRA] Commented: (JGRP-781) NAKACK: regular message not delivered (in some cases) until new message arrives

[Bela Ban (JIRA)]

    [ http://jira.jboss.com/jira/browse/JGRP-781?page=comments#action_12416408 ] 
            
Bela Ban commented on JGRP-781:
-------------------------------

The solution was to keep a counter which is incremented when a regular message is *added*, but not *removed*, e.g. when a message arrives out of order. 

When (more than 1) messages are removed, the counter is decremented.

When an OOB thread sees that the counter is > 0, it actually will remove and process the regular messages., otherwise it returns.

This still allows OOB threads to block, but the chances are not much smaller. However, the ultimate solution is probably to have separate retransmission tables (AckReceiverWindow for UNICAST, NakreceiverWindow for NAKACK) to keep track of OOB and regular messages.

> NAKACK: regular message not delivered (in some cases) until new message arrives
> -------------------------------------------------------------------------------
>
>                 Key: JGRP-781
>                 URL: http://jira.jboss.com/jira/browse/JGRP-781
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Bela Ban
>         Assigned To: Bela Ban
>            Priority: Critical
>             Fix For: 2.7, 2.6.3
>
>
> When we have the following situation, message B3 will not get delivered at A:
> - A and B
> - B sends 3 multicast messages: B1 (regular), B2 (OOB) and B3 (regular)
> - A receives B1, B3, B2
> - A delivers B1
> - B3 has to wait until B2 is received, so the thread returns
> - B2 is received, but since it is OOB, after pushing the message up the stack, the thread terminates !
> ==> B3 will not get delivered until B4 is received !
> The unit test case is OOBTest.testRegularAndOOBMulticasts()

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