[jira] Commented: (AMQ-1807) Activemq stops dispatching messages aborting transaction (STOMP)

["Dejan Bosanac (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/activemq/browse/AMQ-1807?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=48203#action_48203 ] 

Dejan Bosanac commented on AMQ-1807:
------------------------------------

I've committed a change (along with a test case) regarding the prefetch size problem. I've changed "index + 1" with "index", since it is being incremented earlier. All tests are passing. If anyone else can take a look at this as well it would be great.

> Activemq stops dispatching messages aborting transaction (STOMP)
> ----------------------------------------------------------------
>
>                 Key: AMQ-1807
>                 URL: https://issues.apache.org/activemq/browse/AMQ-1807
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Transport
>    Affects Versions: 5.1.0
>         Environment: Linux, JDK 1.6_06b2
>            Reporter: Celso Pinto
>            Assignee: Dejan Bosanac
>            Priority: Critical
>             Fix For: 5.3.0
>
>         Attachments: stomp_test.patch
>
>
> As requested by Dejan Bosanac, I'm adding this ticket. I'm willing to help fix it, ie. I can get my hands dirty, but I must have some pointers on where to look because (unfortunately) I don't have much time to learn ActiveMQ's internals and architecture.
> A copy of the email I sent to the users mailing-list:
> =============================================
> I'm currently struggling to understand the reason behind that's causing the behaviour described in the subject: I'm connecting to activemq via stomp on a python app. Because I need to have the messages rolled back in case of some processing failure I'm wrapping the message processing in the following way:
>  message received -> start transaction -> ack message in transaction ->
> process message -> if no exception commit tx, else rollback transaction
> AFAIK, this is the only way of making message unacknowledgement possible with stomp. Also, this is a single client connection, ie. I'm using a
> single client connection to create a message processing daemon, all messages are sent and received via this single connection to the MQ server.
> Here's a telnet session that can be used to reproduce the problem (open jconsole and send 5 text messages to the queue):
> % telnet localhost 61613
> Trying 127.0.0.1...
> Connected to localhost.
> Escape character is '^]'.
> CONNECT
> ^@
> CONNECTED
> session:ID:starfish-53281-1213736462979-2:2
> SUBSCRIBE
> destination: /queue/testq
> ack: client
> activemq.prefetchSize: 1
> ^@
> MESSAGE
> message-id:ID:starfish-53281-1213736462979-3:3:1:1:1
> destination:/queue/testq
> timestamp:1213736837743
> expires:0
> priority:0
> 1
> BEGIN
> transaction: 1
> ^@
> ACK
> message-id:ID:starfish-53281-1213736462979-3:3:1:1:1
> transaction: 1
> ^@
> MESSAGE
> message-id:ID:starfish-53281-1213736462979-3:4:1:1:1
> destination:/queue/testq
> timestamp:1213736840224
> expires:0
> priority:0
> 2
> MESSAGE
> message-id:ID:starfish-53281-1213736462979-3:5:1:1:1
> destination:/queue/testq
> timestamp:1213736842611
> expires:0
> priority:0
> 3
> ABORT   
> transaction: 1
> ^@
> BEGIN 
> transaction:2
> ^@
> ACK
> message-id:ID:starfish-53281-1213736462979-3:4:1:1:1
> transaction:2
> ^@
> ABORT
> transaction:2
> ^@
> ACK
> message-id:ID:starfish-53281-1213736462979-3:5:1:1:1
> ^@
> I see a couple of issues here:
> #1) even though I specified activemq.prefetchSize to 1 in the subscription command, the connector dispatches two messages in a row
> #2) no more messages are dispatched after aborting the transaction/acknowledging the last received message. Even if the second message isn't wrapped in a transaction, message dispatch stops there.
> To add to the confusion, if I don't use transactions _at all_, my client keeps getting messages, one by one, ie. no two messages are sent together, I only get a new message after ACK'ing the previous one.
> I think I may be stepping into the realms of a buggy STOMP connector. Please tell me if I'm missing something obvious that fixes this issue
> (hence making it a non-issue) or if indeed the STOMP connector has problems.

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