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From Tim Bain <>
Subject Re: Consumers hanging on a queue although there are messages in it
Date Fri, 02 Feb 2018 13:38:35 GMT
Would you be able to use JVisualVM to perform CPU sampling while this is
occurring, to find out what those threads are doing? **WARNING** Do NOT do
CPU *profiling*, which would slow your broker significantly; sampling is
lightweight and generally held to be safe to do against an operational
process, but profiling is very heavyweight. Make sure you're on the right
tab in JVisualVM.


On Feb 2, 2018 12:05 AM, "Stefanic" <> wrote:

> Hi Tim,
> There are no selectors, so there are no messages left behind.
> We have seen this three times now in production and every time when the
> queue is empty (after about 30 minutes of refreshing) the problem goes
> away.
> Threads behavior is rather strange, when the blocking issue is on-going we
> see 1 thread constantly running (100%) in visualvm, and all other threads
> (31 in our case) almost seem synchronized on the same object because all of
> them start running at the same time and go into timed_waiting state at the
> same time.
> That results in 33% running of all other threads and that is not enough to
> keep our queue empty.
> Reproducing this behavior is nearly impossible for us, it occurs randomly
> within about a week.
> Here are the things we tried so far:
> - Downgraded ActiveMQ broker from 5.15.2 to our previous version 5.11.1 but
> the problem occurred again on that version so we assume it is not the
> broker/server
> - Yesterday we downgraded both ActiveMQ and Camel client libraries:
> ActiveMQ
> down to 5.14.5 and Camel from 2.20.1 down to 2.19.4 (I would have rather
> only downgraded 1 at a time but it's our production environment so cannot
> play around too much)
> I will reply here if we experience the blocked state again.
> --
> Sent from:
> f2341805.html

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