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From "James Strachan" <>
Subject Re: Topic and Queue performances
Date Tue, 16 Jan 2007 09:15:52 GMT
On 1/15/07, Rainer Klute <> wrote:
> Rob Davies schrieb:
> > The big difference between topics and queues is that for queues, if
> > the messages have a persistent delivery mode, they are always added to
> > the message store. This is only true for topics if a durable
> > subscriber exists and is interested in that topic.
> Which is not good. If many messages are added to the topic without being
> taken off from the broker by consumers, the memory is soaked up quickly,

Sure - there's a few different solutions for this, plus you can
increase the RAM buffer with the <usageManager>..

> OutOfMemoryErrors occur, and the whole application gets corrupted.

Well it hangs producers until consumers consume stuff to free up space.

> If
> the topic is too full, ActiveMQ should start to swap messages to
> external memory  (disk).

It does :) Though you'll need the latest 4.2-SNAPSHOT to get spooling
to disk for non-persistent messaging.



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