[jboss-jira] [JBoss JIRA] (JGRP-2327) UNICAST3: create receiver table when non-first message is received first

[Bela Ban (Jira)]

     [ https://issues.jboss.org/browse/JGRP-2327?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bela Ban resolved JGRP-2327.
----------------------------
    Resolution: Done


> UNICAST3: create receiver table when non-first message is received first
> ------------------------------------------------------------------------
>
>                 Key: JGRP-2327
>                 URL: https://issues.jboss.org/browse/JGRP-2327
>             Project: JGroups
>          Issue Type: Enhancement
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>            Priority: Major
>             Fix For: 4.1.5
>
>
> * A and B
> * B sends 2 messages to A: B1 and B2
> * A receives B2 _before_ B1 (both B1 and B2 are OOB)
> * The current code has A drop B2 and B1 and send a SEND_FIRST_SEQNO message to B
> * B resends B1, but _not_ B2
> * Retransmission needs to kick in before A receives B2. This might take up to {{xmit_interval * 2}} ms before B2 is retransmitted and delivered
> h4. Scenario (JGRP-2293):
> * A installs a new view
> * B sends a LEAVE-REQ to A (B is leaving, too) on the view installation and a VIEW-ACK for the view. Both messages are unicasts to A and OOB
> * The VIEW-ACK (B2) is received first and dropped, so it will have to be retransmitted
> * This delays the view installation, as A waits for {{view_ack_collection_timeout}} ms until it has received all VIEW-ACKs
> h4. Workaround
> * Set GMS.leave_timeout to a higher value (say 8000ms)
> h4. Solution
> * When B2 is received, and it is not the first message and we don't have a receiver table for B yet, investigate whether we can create the receiver table anyway
> * However, this requires the first seqno from B *to always be 0*
> --> Investigate whether the first seqno in UNICAST3 is always 0, then this solution will work



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