Re: [jgroups-dev] MERGE3 issue

Hi Neal,

comments marked with [bela]

On 25/07/16 08:58, Development issues wrote:
> Hi All.. moving the conversation to the list for all to =96 um =96 ponder=
 ;)
>
> This is interesting, as the merge code is *exactly the same*; MERGE2 or
>
> MERGE3 only trigger a merge, but don't actually execute the merge
> themselves! The merge is done by Merger{2} (in GMS).
>
> /Did not mean to imply the cause was MERGE3.  Yes, they both call Merger.=
 /
>
> Or are you suggesting that the merge is actually never triggered by MERGE=
3?
>
> /No, the merge appears to be triggered.  The results appear to be going
> wrong.  All off the former Coordinators are pointing to other former
> coordinators. /

[bela]
Can you reproduce this scenario? Or describe it? If you give me info such as
A has view BCA
B has view CAB
C has view ABC,

then I can write a unit test to see why this doesn't cause a merge.


> /For example, the output would indicate something like: /
>
> /Host A view: B, X, Y, Z, A  (where B should be coordinator) /
>
> /Host B view: C, Q, R, S, B (where C should be coordinator) /
>
> /Host C view: A, M, N, O, C (where A should be coordinator) /


[bela]
OK, I created https://issues.jboss.org/browse/JGRP-2092 to investigate.


> If you describe how to reproduce the problem, or send me a unit tests,
>
> I'll take a look.
>
> /I am happy to describe the scenario, but it would probably be tough for
> you to reproduce.  We have, for this example, 90 hosts on network A, and
> on networks B-H we have varying numbers, though at least 3 are on all of
> them, and at most 14.  I believe this will reproduce with as few as
> three networks, though we have not seen it with less than 5 of them
> running. /


[bela]
I don't actually care how to reproduce it, but if you can capture the =

views of all members (and their states, e.g. Coord, Participant, Client) =

at the time this happens, then I can write a unit test and see whether =

this situation fixes itself, or whether a bug prevents this from =

happening. This would be done in JGRP-2092.


> Regards,
>
> Neal


-- =

Bela Ban, JGroups lead (http://www.jgroups.org)


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