Re: [jgroups-dev] [javagroups-users] Reception of Multicast message stopped after network restart

OK, I'll try to reproduce this when I return from my vacation.

Meanwhile, can you try this with UDP.loopback="true" ?



[email protected] wrote:
> Hi Bela,
> 	We did the test again using 2.8 GA with UDP as transport (using udp.xml shipped with JGroups 2.8 GA) and it failed 100% of the time. 
>
>     * OS / version : CentOS release 5.3 (Final)
>     * JGroups version : 2.8 GA 
>     * Your config XML file used : udp.xml with shipped with JGroups only Multicast port pour was changed to use 55240
> 	
> Result:
>     A and B form a cluster
>     network restart on A server @ ~ 2010-09-21 11:45:42
>     
>     FROM B: A was suspected by B and excluded A
>     FROM A: B was suspected by A and A start an infinite Suspect/Merge loop, A will never exclude B	
>     From this point A do not receive B multicast messages from B, A is looping on SUSPECT/MERGE. 
>
>     I did a tcpdump and Multicast from B are received on server A but not handle but JGroups (at least not log on TP/UDP). 
>     I also did some threadump on A and Multicast Receiver thread is still running.
>     
>     I attached A and B log with trace log level. 
>
>     PS: Same behavior was observed without manual network restart with same result, we are still working to find reproducible scenarios. 
>
> Thanks 
>     	
>
> David Forget 
>
>
> -----Original Message-----
> From: ext Bela Ban [mailto:[email protected]] 
> Sent: Tuesday, September 21, 2010 8:00 AM
> To: Forget David (Nokia-MS/Montreal)
> Cc: [email protected]; [email protected]
> Subject: Re: Reception of Multicast message stopped after network restart
>
>
>
> [email protected] wrote:
>   
>> How would nodes which stop receiving messages trigger a UDP storm ?
>>
>>
>> DF> This is still under investigation, but quick look at tcpdump show 
>> enndless NAKACK retransmission and
>> lots of SUSPECT from all other nodes that will never stop until all 
>> nodes on the server is restarted.
>>
>>
>>     
>>> We have been able to reproduce the issue with this very simple
>>> scenario on Linux 5.3 64bits.
>>> Scenario: A and B join the same cluster, when everything is stable, We
>>> perform a network restart on server A {/sbin/service network restart}.
>>>       
>
> I ran this scenario on my Fedora based cluster as well: service network 
> start / stop on A (coord of cluster {A,B}). What happened was:
>
>     * A was suspected by B and excluded
>     * A came back
>     * A and B merged back into 1 cluster
>
> This was done with UDP as transport (using udp.xml shipped with JGroups)
>
>
>   
>> I don't think this works: an ifconfig down/up is not something that a
>> socket would survive ! Can you use IP Bonding ?
>>     
>
> I was wrong: apparently this works, at least on Linux and with UDP as 
> transport !
>
>
>   
>>> For an unknown raison node A stop receiving Multicast from B resulting
>>> on an unstable cluster were members could not join the same cluster
>>> anymore. We are reproducing this issue 100% of the time.
>>>       
>
>
> Well, maybe you need to write down the exact steps, and the following info:
>
>     * OS / version
>     * JGroups version
>     * Your config XML file used
>
>
>
>   
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-- 
Bela Ban
Lead JGroups / JBoss Clustering team
JBoss - a division of Red Hat


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Spend less time writing and  rewriting code and more time creating great
experiences on the web. Be a part of the beta today.
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