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From "jiraposter@reviews.apache.org (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (QPID-3604) If the connection is stopped the client should release all it's messages in the prefetch buffer
Date Tue, 15 Nov 2011 22:53:54 GMT

    [ https://issues.apache.org/jira/browse/QPID-3604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13150863#comment-13150863
] 

jiraposter@reviews.apache.org commented on QPID-3604:
-----------------------------------------------------



bq.  On 2011-11-15 16:41:28, Gordon Sim wrote:
bq.  > http://svn.apache.org/repos/asf/qpid/trunk/qpid/java/client/src/main/java/org/apache/qpid/client/AMQSession_0_10.java,
line 787
bq.  > <https://reviews.apache.org/r/2832/diff/1/?file=58392#file58392line787>
bq.  >
bq.  >     Are there any other locks acquired as part of the block here? If so are there
any lock ordering issues where you could be introducing a deadlock?
bq.  
bq.  rajith attapattu wrote:
bq.      Not that I could think of. The message-delivery-lock is taken to ensure that no messages
are being served while we start pulling them out of the queue.
bq.      In my tests so far, I haven't encountered any issues. However I plan to have more
manual tests - ex. Trying to stop the connection while the message consumers are in full flight.
bq.  
bq.  Gordon Sim wrote:
bq.      What about the failover mutex? Could the release trigger a codepath that attempts
to acquire that? What about an asynchronous exception occurring concurrently; would that ever
need to acquire the message-delivery-lock?
bq.  
bq.  rajith attapattu wrote:
bq.      Certainly possible as mentioned in the comment below. The failover and the synchronous
exceptions are things that could trigger a deadlock.
bq.      Testing is the best way to eliminate these possibilities. However IMO acquiring the
message-delivery-lock is a must to ensure unwanted interaction between messages delivery &
releasing.

Testing is certainly vital, however with threading issues a thorough analysis is as well given
the non-deterministic nature of potential problems.


- Gordon


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/2832/#review3264
-----------------------------------------------------------


On 2011-11-15 15:36:36, rajith attapattu wrote:
bq.  
bq.  -----------------------------------------------------------
bq.  This is an automatically generated e-mail. To reply, visit:
bq.  https://reviews.apache.org/r/2832/
bq.  -----------------------------------------------------------
bq.  
bq.  (Updated 2011-11-15 15:36:36)
bq.  
bq.  
bq.  Review request for qpid, Gordon Sim, Robbie Gemmell, Weston Price, and Oleksandr Rudyy.
bq.  
bq.  
bq.  Summary
bq.  -------
bq.  
bq.  This attempts to fix one of the issues related to the handling of Message credits. See
QPID-3602 for an overall picture of the various issues.
bq.  
bq.  This particular patch does the following.
bq.  1. When the connection is stopped, it sends message.stop() & releases all messages
in the prefetch buffer.
bq.  2. It will also release any messages (that were in flight) that comes after the connection
is stopped. (*)
bq.  
bq.  (*) This interferes with the immediate_prefetch feature. However I don't know if immediate
prefetch is really required in the 0-10 path.
bq.  
bq.  As always comments, suggestions & criticisms are equally welcomed.
bq.  
bq.  
bq.  This addresses bug QPID-3604.
bq.      https://issues.apache.org/jira/browse/QPID-3604
bq.  
bq.  
bq.  Diffs
bq.  -----
bq.  
bq.    http://svn.apache.org/repos/asf/qpid/trunk/qpid/java/client/src/main/java/org/apache/qpid/client/AMQSession_0_10.java
1202228 
bq.    http://svn.apache.org/repos/asf/qpid/trunk/qpid/java/client/src/main/java/org/apache/qpid/client/BasicMessageConsumer_0_10.java
1202228 
bq.    http://svn.apache.org/repos/asf/qpid/trunk/qpid/java/systests/src/main/java/org/apache/qpid/client/prefetch/PrefetchBehaviourTest.java
1202228 
bq.    http://svn.apache.org/repos/asf/qpid/trunk/qpid/java/client/src/main/java/org/apache/qpid/client/AMQConnection.java
1202228 
bq.  
bq.  Diff: https://reviews.apache.org/r/2832/diff
bq.  
bq.  
bq.  Testing
bq.  -------
bq.  
bq.  See PrefetchBehaviourTest#testConnectionStop for more details.
bq.  
bq.  
bq.  Thanks,
bq.  
bq.  rajith
bq.  
bq.


                
> If the connection is stopped the client should release all it's messages in the prefetch
buffer
> -----------------------------------------------------------------------------------------------
>
>                 Key: QPID-3604
>                 URL: https://issues.apache.org/jira/browse/QPID-3604
>             Project: Qpid
>          Issue Type: Bug
>          Components: Java Client
>    Affects Versions: 0.14
>            Reporter: Rajith Attapattu
>            Assignee: Rajith Attapattu
>             Fix For: 0.15
>
>
> When connection.stop() is called, the JMS client should release all it's messages in
the prefetch buffer.
> For all we know, the connection may never be started (depending on application logic)
and those messages will be stuck on the prefetch buffer. Releasing it will allow another consumer
to get them (in the case of a shared queue case).
> Another less severe but nevertheless an undesirable side affect of this is the client
getting more messages than required by the capacity or prefetch arguments. See QPID-3602
> This may not be a big issue if the client is prefetching a few messages, but if prefetching
something like 5000 messages, this could potentially cause a lethal spike in the clients memory
usage.
> Even in low capacity/prefetch values, if the messages are large (say in the mega byte
range) this could potentially put the client under memory pressure.

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