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From: Donnell Alwyn <Alwyn.Donnell@uk.mizuho-sc.com>
To: "'users@activemq.apache.org'" <users@activemq.apache.org>
Subject: RE: Messages in queue but not consumed
Thread-Topic: Messages in queue but not consumed
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Date: Thu, 3 Jul 2014 09:53:04 +0000
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I had a similar issue in ActiveMQ 5.7.=20

Messages stuck on the pending queue would never come off, new messages woul=
d process ok. A broker restart was required to get messages off the pending=
 queue.

Upgrading to 5.9 solved my problem.

Regards
Alwyn

------------------------------------------------------------------------
Alwyn Donnell

ISD Middleware and Architecture
Mizuho International
Bracken House
1 Friday Street
London EC4M 9JA

email: alwyn.donnell@uk.mizuho-sc.com
Tel.: +44 (0)20 7090 6569


-----Original Message-----
From: Rahn Nicholas, Bedag [mailto:Nicholas.Rahn@bedag.ch]=20
Sent: 03 July 2014 10:27
To: 'users@activemq.apache.org'
Subject: Messages in queue but not consumed

We've noticed a problem in our production ActiveMQ 5.8 instances where mess=
ages remain in a queue even when there are active consumers on that queue. =
Most messages are consumed by the consumers, but a few do not and remain in=
 the queue. They just seem to be stuck there.  Here's our setup:

-       2 instances of ActiveMQ 5.8 in a failover (master/slave) setup on l=
inux
-       JDBC (MSSQL) for the message store

I've been able to reproduce this situation manually by doing the following:

1.      Create 2 consumers on a queue.
2.      Run 2 Producers (from 2 separate processes) simultaneously to send =
1000 messages each to the queue.
3.      Use JMX to check the QueueSize of the queue.

Not everytime, but every second or third run of the 2 simultaneous producer=
s, not all of the 2000 messages will be consumed.  When this happens, the c=
onsumers are still running and idle, but the QueueSize is non-zero (can be =
anything from 1 - 5, usually) and I can see the messages in the database. T=
he unconsumed messages do not stop later messages from being consumed, howe=
ver. A broker restart causes the 'stuck' messages to be immediately sent to=
 the consumers.

It seems to have something to do with the multiple simultaneous producers a=
s running just 1 producer at a time works as normal with all messages consu=
med. I have tried to create a self-contained unit test (i.e. vm broker) for=
 this, but was not able to reproduce the situation. However, a unit test co=
nnecting to a remote broker did show the same situation (with many more stu=
ck messages). That would lead me to guess that the issue is perhaps in the =
JDBC store code, but that's just a guess.

Is this a known issue?  Is there any workaround for it? Is it corrected in =
a version later than 5.8?

Thanks for the help.
Nick


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