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From Antoine Chevin <antoine.che...@gmail.com>
Subject Re: Testing failover on dispatcher/java-broker cluster
Date Thu, 15 Sep 2016 08:56:33 GMT
Hi Ted,

You’re right, the connection close looked strange before stopping of the
broker. I manually added the annotation (# stopping the broker) and was
wrong about the position of this one. I replayed the test and the
connection close happens *after* the broker stop. I assume it is the broker
that initiates it.

I found something interesting. In my test, I always sent a message when the
broker is down, expecting to get a JmsSendTimedOutException (waiting for
the disposition frame). I assumed this was harmless. But it turns out this
is not. When I don’t do that, I can send a message after the broker
restart. So to sum up the experiment I did:

* I use Wireshark between the JMS client and the dispatcher. *

1)      Using JMS I establish a connection to the dispatcher and create a
message producer (Wireshark: connection open -> attach)
2)      I’m able to send a message to the broker through the dispatcher (
Wireshark: transfer -> disposition)
3)      I stop the broker
4)      With the same link, I send a message and I get a
JmsSendTimedOutException (waiting for the disposition frame) (Wireshark:
transfer)
5)      I restart the broker
6)      With the same link, I try to send a message and I get a
JmsSendTimedOutException for the same reason (waiting for the disposition
frame) (Wireshark: transfer)

If I skip step (4), I cannot reproduce step (6) and my messages arrive
(Wireshark: transfer -> disposition) to the restarted broker.

I hope it makes it clearer for you. Sorry for my rookie mistakes :-).

Note: My colleague and I ran a small experiment to identify if the problem
comes from JMS or the AMQP protocol. He changed the code of the java broker
to not send the disposition frame one time out of two.

We got these results:

* I use Wireshark between the JMS client and the patched broker. *

1) Using JMS I establish a connection to the patched broker and create a
message producer (Wireshark: connection open -> attach)
2)  I send a message to the broker and it replies with the disposition
frame (Wireshark: transfer -> disposition)
3) I send a message to the broker which drops the disposition frame. I get
a send timeout in JMS (Wireshark: transfer)
2)  I send a message to the broker and it replies with the disposition frame
(Wireshark: transfer -> disposition). It works fine.

We assume that there is something going on in the dispatcher.


Thanks,
Antoine

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