[jboss-jira] [JBoss JIRA] (JGRP-1659) deadlock in MFC with default configuration

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1659?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12790780#comment-12790780 ] 

Bela Ban commented on JGRP-1659:
--------------------------------

I can add a sanity check that issues a warning if frag_size is less than max_credits * min_threshold. In addition, with ergonomics enabled, the value(s) could be adjusted automatically.
                
> deadlock in MFC with default configuration
> ------------------------------------------
>
>                 Key: JGRP-1659
>                 URL: https://issues.jboss.org/browse/JGRP-1659
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 3.2.7
>            Reporter: Mircea Markus
>            Assignee: Bela Ban
>             Fix For: 3.4
>
>         Attachments: expiration-test.zip
>
>
> MFC.down does the following:
> {code:java}
>             credits.decrement(length, block_time); //A
>             if(needToSendCreditRequest()) //B
>                     sendCreditRequest(tuple.getVal1(), Math.min(max_credits)
> {code}
> A blocks forever even if the MFC.max_block_time is configured:
> {code:xml}
> <MFC max_credits="200k" min_threshold="0.20" max_block_time="1"/>
> {code} 
> This happens at the same time on the whole cluster. B never gets invoked, so both wake up conditions( credits received or timeout) for credits.decrement are never satisfied resulting in the whole cluster to freeze.

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