[infinispan-dev] Put issues with newly joining node

[Bela Ban]

On 12/4/12 11:30 AM, Dan Berindei wrote:
> BTW, I also got an exception yesterday in MarshallExternalPojosTest and
> I investigated it, but in my case the error was much weirder: two nodes
> both opened a TCP connection to each other, yet none of them received
> the forwarded command. I've asked Bela to investigate as well, but he
> didn't find anything suspicious in JGroups.

If a node A connects to B and B connects to A at the exact same time 
(and there wasn't any existing connection between the 2 nodes, then one 
of the 2 will 'win' and the other one will close its connection. The 
message to be sent is then lost.

This is corrected by one of the upper layers, e.g. UNICAST retransmits 
the message until it gets an ack. Re-sending a message will then create 
a new connection, if the existing one was closed / removed.

However, with UNICAST2, if a given message was the last message and no 
further messages are sent, then only UNICAST2's stability messages will 
detect that the other node is missing the last message sent. Stability 
is triggered every 60 seconds by default, so unless that property was 
changed, or stability was triggered programmatically, that last (lost) 
message won't get retransmitted for 60 seconds.

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