[jboss-jira] [JBoss JIRA] (JGRP-1902) Simplify failure detection and merge timeout configuration

[Dan Berindei (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13040875#comment-13040875 ] 

Dan Berindei commented on JGRP-1902:
------------------------------------

{{timeout}} doesn't work like that in {{FD_ALL}} and {{FD_ALL2}}. {{FD_ALL}} checks the timeout every {{timeout_check_interval}} millis, so the maximum failure detection time is {{timeout + timeout_check_interval}} millis. {{FD_ALL2}} only checks the timeout every {{timeout}} millis, so the maximum detection time is {{2 * timeout}} millis.

I believe messages getting lost only affects the _minimum_ failure detection time (and the chance of false positives).

> Simplify failure detection and merge timeout configuration
> ----------------------------------------------------------
>
>                 Key: JGRP-1902
>                 URL: https://issues.jboss.org/browse/JGRP-1902
>             Project: JGroups
>          Issue Type: Enhancement
>    Affects Versions: 3.6
>            Reporter: Dan Berindei
>            Assignee: Bela Ban
>            Priority: Minor
>             Fix For: 3.6.2
>
>
> FD/FD_ALL/FD_ALL2/FD_SOCK javadoc doesn't give any guidance as to how long it would take to detect a leaving member. MERGE2/MERGE3 javadoc also doesn't say how much it would take to detect that the network has healed.
> For an example of how misleading the current settings can be, I have seen MERGE3 take more than 20s to merge two partitions with min_interval=1000 and max_interval=5000. FD also detects a leaver after {{timeout * max_tries}} in the best case, and twice that if 2 consecutive nodes (in the members list) leave at the same time.
> The maximum time it takes to detect a leaver is of particular interest to Infinispan users, because Infinispan is supposed to protect against nodes leaving. But if the users don't configure a high enough RPC timeout in Infinispan, we don't get to detect the node leaving.
> Ideally, the user should be able to specify a maximum detection time, and the protocol should adjust the existing settings to meet that (most of the time).



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