[jboss-jira] [JBoss JIRA] (JGRP-1461) SEQUENCER leaks sequence numbers

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1461?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12691757#comment-12691757 ] 

Bela Ban commented on JGRP-1461:
--------------------------------

Re: ordering:
If we have 2 message B5 and B6 multicast by B (by the same thread), then B5 will be delivered before B6 everywhere (although messages from other members could sneak in between the 2).

This is so because B5 is forwarded to the coordinator (A) via UNICAST. When the send(B5) returns, the unicast message has been assigned a seqno and sent to A. Therefore the send(B6) will get the next seqno in UNICAST. This means that B5 will be delivered by A *before* B6 as UNICAST orders these 2 messages.

When processing B5, A broadcasts a message A45. This message is also assigned a seqno that is lower than the seqno assigned form B6 (say it is sent as A50). Therefore we are guaranteed that A46 (B5) is delivered everywhere *before* A50 (B6).

When we have different threads sending messages in B concurrently, then the message will be TO-delivered everywhere in the order in which they are assigned seqnos in UNICAST. This is the same behavior as if those messages were sent via NAKACK.
                
> SEQUENCER leaks sequence numbers
> --------------------------------
>
>                 Key: JGRP-1461
>                 URL: https://issues.jboss.org/browse/JGRP-1461
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 3.0.9, 3.1
>            Reporter: David Hotham
>            Assignee: Bela Ban
>             Fix For: 3.0.10, 3.1
>
>
> As noted in JGRP-1458, it looks as though SEQUENCER always thinks that sequence numbers must start at zero.  But a member who joins a group after some messages have already been broadcast may never receive sequence number zero.  So, I think, his SeqnoTable will grow indefinitely.
> Note that this one's mostly through code reading.  I think I'm right; but I'm happy to be told otherwise!
> Pull request to follow shortly.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.jboss.org/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira