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From "Gabriel Gerhardsson (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (AMQ-4022) SEND directly after SUBSCRIBE causes bad state -> no DISCONNECT receipt
Date Tue, 11 Sep 2012 13:41:08 GMT

     [ https://issues.apache.org/jira/browse/AMQ-4022?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gabriel Gerhardsson updated AMQ-4022:
-------------------------------------

    Attachment: AMQ_4022_possible_fix.diff

Attached patch is a possible fix. With this applied, I haven't been able to reproduce the
problem.
                
> SEND directly after SUBSCRIBE causes bad state -> no DISCONNECT receipt
> -----------------------------------------------------------------------
>
>                 Key: AMQ-4022
>                 URL: https://issues.apache.org/jira/browse/AMQ-4022
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: stomp
>    Affects Versions: 5.5.1
>         Environment: SLES11-SP1 x86_64
>            Reporter: Gabriel Gerhardsson
>         Attachments: AMQ_4022_possible_fix.diff, amqtest.pl, Net_Stomp.pm.diff
>
>
> Executive summary
> ---
> A message is lost, the connection ends up in a strange state, and then when the client
sends DISCONNECT it gets no receipt.
> Details
> ---
> Steps to reproduce:
> 1) Using STOMP
> 2) Send a SUBSCRIBE message with destination=/topic/foo, without asking for a receipt.
No other options sent in message.
> 3) Send a message to /topic/foo, without asking for a receipt.
> 4) Wait 10ms for message
> 5) Go right ahead and send DISCONNECT message, asking for a receipt.
> 5.1) About 20% of the time, no DISCONNECT receipt is received, however long the client
waits. This seems to coincide with the case when the message doesn't arrive in #4.
> 5.2) It does look like ActiveMQ gets the DISCONNECT message tho since it unsubscribes
the client from /topic/foo at that timestamp.
> The DISCONNECT receipt getting lost is clearly a bug. Waiting for the receipt is important
since I've seen cases where the client isn't unregistered properly in ActiveMQ if the client
just sends DISCONNECT and then closes the socket.
> Test script
> ---
> Apply the small patch to the perl library Net/Stomp.pm
> It's a naive minimal patch to make it wait for a receipt for the DISCONNECT message.
It will actually just wait for any frame to arrive and won't check what it is, but it's enough
for this test.
> Run amqtest.pl a few times. A non-buggy run completes almost immediately. A buggy run
hangs the script during disconnect.
> Workaround
> ---
> -When sending the SUBSCRIBE with receipt requested, and waiting for the receipt before
sending the SEND, I was unable to reproduce the issue, even after running the script 100000
times.-
> No, it turns out that the workaround suggested above does not completely eliminate the
problem. It probably just introduces a large enough delay to almost always avoid the race
condition. After 30000 additional test runs with the script the error occured again.

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