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From Timothy Bish <>
Subject Re: Subscriber losing messages (from topic)
Date Thu, 10 Jan 2013 20:59:52 GMT
On Thu, 2013-01-10 at 21:52 +0100, Karel Gardas wrote: 
> Hello,
> I'm playing a bit with ActiveMQ 5.7.0 and found that under some
> circumstances my subscriber looks like losing messages which are
> delivered to him from the broker. Honestly speaking I don't know if to
> blame subscriber or broker in this case but while looking into web
> console of the broker, the broker claims the messages are delivered, but
> I don't see them on subscriber. It took me some time to duplicate this
> issue on as simple as possible example, but finally I've been able to a
> bit hack activemq's own demo to duplicate it.
> If you'd like to see the same effect as I see now, just go to
> activemq/example/src and add:

You should try to create a unit test to represent what's going on so
that we can take closer look.  Seems odd that the sleep would cause
something to get lost unless there's a TTL set on the messages. 

> try {
> Thread.sleep(1);
> }
> catch (Exception ex) {
> ex.printStackTrace();
> }
> into's onMessage method. This will ensure that
> onMessage on consumer will run a little bit slower than producer is able
> to send messages and you will see the effect.
> Once done, just run consumer with:
> ant consumer -Dtopic=true -Dverbose=false -Dmax=1000000 -Dsubject=TRM
> and producer with:
> ant producer -Dtopic=true -Dverbose=false -Dmax=1000000 -Dsubject=TRM
> if everything is working well, then both consumer and producer should
> end once delivering 1000000 messages. The problem is that consumer does
> not end due to losing some of the messages somewhere. If this does not
> happen on your box, please increase number of milliseconds on
> Thread.sleep to make onMessage even slower. I'm running this on Solaris
> 11/JDK 1.7 on Xeon E5 2.0 GHz here.
> Now, I do have following questions:
> - am I right assuming the example above should really deliver all the
> messages to the consumer onMessage method?
> - is this already known issue or shall I report it properly to
> ActiveMQ's bug tracking system?
> Just to make sure, I've also tried running consumer with ant consumer
> -Dtopic=true -Dverbose=false -Dmax=1000000 -Dsubject=TRM
> -Durl="tcp://localhost:61616?jms.prefetchPolicy.queuePrefetch=0" -- but
> it neither helps. At least I've thought pre-fetching might cause this so
> I tried...
> BTW: I've seen the same issue but not on demo, but on our own
> application also while running subscriber on top of 5.6.0 and 5.5.0
> releases. I always used 5.7.0 release for broker and producer though.
> I've not seen it on demo as I've not tested this with older releases but
> I would guess the issue will be there too.
> Thanks a lot for any idea about what's going wrong here.
> Karel
> PS: resending as my former subscription to the list looks like stuck in 
> the middle of the way. Sorry if it went through already.

Tim Bish
Sr Software Engineer | RedHat Inc. | | 
skype: tabish121 | twitter: @tabish121

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