[jboss-jira] [JBoss JIRA] (JGRP-2451) FD_ALL2: improvements

[Bela Ban (Jira)]

     [ https://issues.redhat.com/browse/JGRP-2451?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bela Ban updated JGRP-2451:
---------------------------
    Summary: FD_ALL2: improvements  (was: FD_ALL3)


> FD_ALL2: improvements
> ---------------------
>
>                 Key: JGRP-2451
>                 URL: https://issues.redhat.com/browse/JGRP-2451
>             Project: JGroups
>          Issue Type: Feature Request
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>            Priority: Major
>             Fix For: 5.0, 4.2.0
>
>
> New heartbeat protocol, based on {{FD_ALL2}}. 
> * Messages should count as heartbeats ({{msg_counts_as_heartbeat}} should be default, and as such, deprecated).
> * When a multicast message is sent before {{interval}} elapsed, we suppress sending a heartbeat
> * A simple bitmap represents members: bits set to {{1}} mean we received a heartbeat since the last check (at {{timeout}} ms), bits set to {{0}} lead to suspicions
> * The bitmap is reset on each check
> It is crucial that setting a bit in the bitmap is quick (not like in {{FD_ALL}}, where we fetch the current time from the time service), especially since this is done on every message.
> The advantage of {{FD_ALL3}} over previous failure detection protocols is that we only send heartbeats when there is no (multicast) traffic, and we don't suspect a member P when heartbeats have been missing despite receiving traffic from P.
> We need to think about whether to consider unicast messages, too, on the sender side: we could populate a bit map with messages sent to members: on a unicast message to P, P's bit would be set in the bit. On a multicast message, all bits would be set. Then, we could selectively send heartbeats only to members with bits set to 0.
> However, this is only feasible with sending a message N-1 times (e.g. TCP); for UDP we don't have such an 'anycast' available.



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