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From "James Strachan" <>
Subject Re: activemq hangups
Date Thu, 20 Jul 2006 05:59:55 GMT
Hangs can happen when using non-persistent messaging; its a common
problem with having slow consumers....

another workaround is just to increase the usageManager's RAM pool -
see the <usageManager> setting in the example XML

more inline...

On 7/18/06, Christopher Mihaly <> wrote:
>    1). When I brosed the topic itself, it looks like every message is in
> there.   There were a lot of messages.  Is there a limit to how many
> messages can be in a topic?

No - though there is a RAM limit for non-persistent queues and topics

>     2). That said, some of those message should have been cleaned up because
> all subscribers had read them.  When do messages get cleaned out and how?
> Do I have to set something up to do this?

No it should just happen - its quite asynchronous though due to the
delay in checkpointing from the journal to JDBC and then the timer
fires to clear down any durable topics which have been acknowledged by
all interested subscribers.

I suspect the lockups are more likely to be the non-durable subscribers.

>     3). Is there something I can set, a debuging state, that might tell me
> what is happening when it gets stuck?  Is there something I can do the next
> time it gets stuck to figure out why.  Right now, this is a problem because
> things break when this happens, I miss messages and then we loose message
> when I destroy and create messages.

The best thing is to watch the state of the system with JMX...

But I'd start off by adding a zero or two to the usageManager's RAM
buffer (and having a fairly big heap).



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