[jboss-jira] [JBoss JIRA] (JGRP-1743) NAKACK*: log a warning if xmit_table gets large

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1743?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12923866#comment-12923866 ] 

Bela Ban commented on JGRP-1743:
--------------------------------

This is problematic: what is huge and when should this check be done? 
* Is it the number of messages in the NAKACK table ? 
* Is it the entire size occupied by the NAKACK table ? In the latter case, I'd have to iterate through all messages and get their length. This is already provided via {{NAKACK2.getSizeOfAllMessages()}}.
* When should this be done ? Periodically ? Note that the above method is exposed as a JMX operation, so it could be queried from a script, e.g. {{probe.sh op=NAKACK2.getSizeOfAllMessages}}

                
> NAKACK*: log a warning if xmit_table gets large
> -----------------------------------------------
>
>                 Key: JGRP-1743
>                 URL: https://issues.jboss.org/browse/JGRP-1743
>             Project: JGroups
>          Issue Type: Feature Request
>    Affects Versions: 3.4.1
>            Reporter: Dennis Reed
>            Assignee: Bela Ban
>            Priority: Minor
>             Fix For: 3.5
>
>
> There have been some cases where NAKACK* accumulates large number of messages, causing OutOfMemoryErrors.
> Large numbers of messages in NAKACK* would almost always indicate a problem, which the user should be aware of.
> Logging a warning if the number of messages in NAKACK passes a configurable threshold would let the user investigate and take action sooner before a catastrophic OutOfMemoryError, or other issues occur.

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