Thank you for the links. So far I've failed to wrap my head around it,
unfortunately.
I read that setUseCache(false) and setExpireMessagesPeriod(0) and
prefetchPolicy.all=0 should achieve true priority dispatching, but they
didn't.
I have brokerService.setPersistent(false) so I'm not sure how "page in from
the store for dispatch" affects my case. But when I call
"removeMatchingMessage()" which calls "doPageIn(true)", my high priority
messages suddenly get processed so you're probably right.
When the case happened, I enabled debug logging and got this output:
2020-09-17 13:29:00.864 DEBUG 8380 --- [ActiveMQ
BrokerService[localhost] Task-113] o.a.a.b.r.Queue
: queue://task.standard, subscriptions=200, memory=2%, size=214678,
pending=0 toPageIn: 200, force:false, Inflight: 200, pagedInMessages.size
201070, pagedInPendingDispatch.size 200870, enqueueCount: 258397,
dequeueCount: 43719, memUsage:2322435451, maxPageSize:200
Can anyone see why this would cause my high priority messages not being
paged in?
Also I'd like to mention that I don't need "strict" dispatching; if a few
low-prio messages slip in before the high-prio ones, that's ok. But it
can't be that during hours, ten to hundreds of thousands low-prio messages
get dispatched first until all that's left are high-prio messages.
Any help is much appreciated!
On Thu, Aug 20, 2020 at 1:26 PM Gary Tully <gary.tu...@gmail.com> wrote:
> There is a lot of relevant detail in
> https://issues.apache.org/jira/browse/AMQ-6215 and a test case that shows
> how to best achieve true priority dispatch. It is always a trade off
> between page in from the store for dispatch (or other reasons to have
> messages in memory) and prefetch to active consumers.
>
> note some of the scenarios in this test:
>
> https://git-wip-us.apache.org/repos/asf?p=activemq.git;a=blob;f=activemq-unit-tests/src/test/java/org/apache/activemq/usecases/QueueZeroPrefetchLazyDispatchPriorityTest.java
>
> that may help you understand what is in play and point to the best
> approach.
>
> On Thu, 20 Aug 2020 at 07:31, Michel Jung <michel.jun...@gmail.com> wrote:
>
> > Hi all,
> >
> > My software uses prioritized messages and it's working just fine – until
> it
> > doesn't.Some unknown condition leads to my higher prioritized messages
> not
> > getting processed until I either remove at least a single message from
> the
> > queue, or until all other messages have been processed.
> >
> > I posted this on StackOverflow (
> >
> >
> https://stackoverflow.com/questions/63483621/activemq-why-do-my-messages-get-stuck-in-storequeuecursor
> > ).
> >
> > Is it ok if I just link it rather than repeating it here?
> >
> > I'm quite desperate to solve this and would really appreciate it if
> someone
> > more competent in this area could point me in the right direction. Thank
> > you very much.
> >
> > Michel
> >
>
