[jboss-jira] [JBoss JIRA] (JGRP-1963) TCP_NIO2 starts dropping messages

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13106922#comment-13106922 ] 

Bela Ban commented on JGRP-1963:
--------------------------------

Ok, so here's what happens:
* Apparently an {{OP_CONNECT}} flag on an already connected channel leads to a loop with {{select()}} always returning 0
* So {{OP_CONNECT}} has to be cleared. However...
* While {{OP_CONNECT}} is cleared in the select-loop, {{OP_READ}} is added by reading the old value of interestOps (still {{OP_CONNECT}} !) and anding it with {{OP_READ}} --> {{OP_CONNECT | OP_READ}}
* This is because {{SelectionKey.interestOps(ops)}} is not thread safe.
SOLUTION: write a method to change the selection key which is thread safe and has to be used by all threads

> TCP_NIO2 starts dropping messages
> ---------------------------------
>
>                 Key: JGRP-1963
>                 URL: https://issues.jboss.org/browse/JGRP-1963
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 3.6.5
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>            Priority: Critical
>             Fix For: 3.6.6
>
>
> At some point, {{TCP_NIO2}} starts dropping messages, at either the send or receive direction (still need to find out). This shows itself when e.g. a JOIN fails: the joiner sends a lot of {{JOIN-REQ}} messages and gets {{JOIN-RSP}} msgs from the coord, but doesn't receive them.
> If {{GMS.max_join_attempts="0"}}, then this goes on forever, or until the joiner doesn't discover any nodes anymore.
> {{probe.sh jmx=UNICAST3.printConnections}} shows that messages are sent but no acks are received.
> Clearing the connection table in {{TCP_NIO2}} fixes the problem: {{probe.sh op=TCP_NIO2.clearConnections}}. 
> This shows that the issue is indeed in {{TCP_NIO2}}. Also, {{TCP}} and {{UDP}} work.



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