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From Tim Bain <tb...@alumni.duke.edu>
Subject Re: ** JMS Client HANGING - AMQ 5.9, AIX 6.1
Date Sat, 27 Jun 2015 14:38:58 GMT
Carlos,

Although the suggestions Paul and I gave are good solutions to a number of
problems that you MIGHT have, I think it's important first to figure out
what problem(s) you DO have before you go changing a bunch of stuff that
might or might not apply.

The first question you need to answer is whether you have a memory leak
(i.e. a continual increase in memory usage that will eventually run you out
of memory no matter what JVM size or GC strategy you use) or simply a
non-increasing memory usage that happens to be hitting lots of full GCs.
In either of those situations, you also need to characterize and understand
your memory usage so you can figure out what uses memory and how much it
uses.

The second question you need to answer is whether there is any indication
of misbehavior by the ActiveMQ broker or by the ActiveMQ client code that
runs in your client process.

Once you know those things, you can decide which ones of the suggestions
Paul and I gave are appropriate for you to apply.

Tim
On Jun 26, 2015 9:53 AM, "Paul Gale" <paul.n.gale@gmail.com> wrote:

> Carlos,
>
> You appear to running ActiveMQ 5.9.0 on Java 6 both of which are quite old.
> Trying upgrading to the latest ActiveMQ (5.11.1) with Java 7 or 8 and, as
> Tim pointed out, enable the G1GC garbage collector. Once you've done that
> remove the -Xms and -Xmn flags. See if that helps.
>
> On the off chance the broker is being asked to handle messages that are
> larger than you're expecting add the option
> wireFormat.maxFrameSize=<some_byte_value> to the TCP/NIO transport
> connector definition in activemq.xml. This will cause the sending of
> messages larger than the configured threshold to fail.
>
>
> Thanks,
> Paul
>
> On Fri, Jun 26, 2015 at 10:01 AM, Tim Bain <tbain@alumni.duke.edu> wrote:
>
> > The stack trace you quoted is irrelevant; it's just executors waiting to
> be
> > given work to do.  There are also lots of threads trying to read messages
> > from sockets in
> > org/apache/activemq/transport/tcp/TcpBufferedInputStream.fill() or
> waiting
> > for a message to be available during a call to
> > org/apache/activemq/SimplePriorityMessageDispatchChannel.dequeue(); both
> of
> > those are also irrelevant, because they're just ActiveMQ waiting to be
> > given work.
> >
> > There are two threads waiting for responses to synchronous sends in
> > org/apache/activemq/ActiveMQConnection.syncSendPacket().  Those might
> > simply be victims of the inability to read messages, or they might be
> > relevant to what's going on; it's hard to tell from what you've sent.
> One
> > thing I'd check based on them (and one thing I'd always check in general,
> > so hopefully you've already done this) is whether there are any errors in
> > the ActiveMQ broker logs, and specifically whether there are any messages
> > about producer flow control kicking in.  Depending on how PFC is
> > configured, I believe I've seen at least one JIRA or wiki page describing
> > the potential for PFC to cause deadlock when synchronous sends are used
> by
> > preventing the acks from being read.  If you see PFC-related lines in the
> > broker logs, we'll go from there; if not, then don't worry about this.
> >
> > My overall thought, however, is that ActiveMQ (and the Spring JMS library
> > you're using) on its own isn't likely to run your client out of memory
> > unless your messages are VERY large, because there are limits on how many
> > messages will be transferred to your client at any one time.  Plus this
> > code has been run by LOTS of people over the years; if it caused OOMs on
> > its own, the cause would almost certainly have already been found.  So
> it's
> > most likely that this behavior is caused by something your own code is
> > doing, and the most likely guess is that you may be wrongly holding a
> > reference to objects that could otherwise be GCed, increasing heap memory
> > over time till you eventually run out.  You'll probably want to use tools
> > such as JVisualVM to analyze your memory usage and figure out what
> objects
> > are the ones causing it to grow and what's holding a reference to them.
> >
> > One other possibility is that your algorithm is correct, but processing
> > each message is memory-intensive (using over half the heap in total
> across
> > however many messages you're processing in parallel) and so lots of
> objects
> > are getting forced into Old Gen even though they're actually short-lived
> > objects, and they are only getting removed from Old Gen via full GCs.  I
> > think this is far less likely than the other things I've described, but
> if
> > it's the problem, you could 1) increase the JVM's heap size if possible,
> 2)
> > tweak the percentages allocated to Old Gen and Young Gen to give more to
> > Young Gen in the hopes that more things will stay in Young Gen for
> longer,
> > or 3) look into other GC strategies (I'd recommend G1GC, but you appear
> to
> > be on the IBM JVM and I've never used it or researched it so I don't know
> > what GC strategies it offers).  But I think you'd really want to prove to
> > yourself that this is your problem (i.e. that none of the other things
> I've
> > mentioned are) before you go down this path, because throwing more memory
> > at a memory leak doesn't fix it, it just delays it and makes it harder to
> > troubleshoot.
> >
> > Tim
> >
> > On Fri, Jun 26, 2015 at 1:53 AM, cdelgado <carlos.delgado@proyecti.es>
> > wrote:
> >
> > > Hi all,
> > >
> > > We're facing an issues that is stopping us for going to production,
> this
> > is
> > > a huge blocker for us.
> > >
> > > The problem is that one of our consumers is hanging (randomly,
> aparently)
> > > and stops consuming messages. From a JMX we can see that is consuming
> > > memory
> > > and performing quite a lot full GCs.
> > >
> > > I'm attaching a javacore dump generated sending a kill -3 to the
> process.
> > > There you can see all the details and thread statuses.
> > >
> > > javacore.txt
> > > <http://activemq.2283324.n4.nabble.com/file/n4698204/javacore.txt>
> > >
> > > Basically, we have 90.7% of the threads waiting on condition, 3.5%
> Parked
> > > and 5.7% Running.
> > >
> > > The Parked threads have different stacktraces, but generally they end
> in
> > > the
> > > same block:
> > >
> > > *at sun/misc/Unsafe.park(Native Method)
> > > at
> > >
> > >
> >
> java/util/concurrent/locks/LockSupport.parkNanos(LockSupport.java:222(Compiled
> > > Code))
> > > at
> > >
> > >
> >
> java/util/concurrent/SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:435(Compiled
> > > Code)) *
> > > at
> > >
> > >
> >
> java/util/concurrent/SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:334(Compiled
> > > Code))
> > > at
> > >
> > >
> >
> java/util/concurrent/SynchronousQueue.poll(SynchronousQueue.java:885(Compiled
> > > Code))
> > > at
> > >
> > >
> >
> java/util/concurrent/ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:966(Compiled
> > > Code))
> > > at
> > >
> > >
> >
> java/util/concurrent/ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:928)
> > > at java/lang/Thread.run(Thread.java:761)
> > >
> > > Any *quick* help would be much appreciated, I'm a bit ost here.. :S
> > >
> > > Carlos
> > >
> > >
> > >
> > > --
> > > View this message in context:
> > >
> >
> http://activemq.2283324.n4.nabble.com/JMS-Client-HANGING-AMQ-5-9-AIX-6-1-tp4698204.html
> > > Sent from the ActiveMQ - User mailing list archive at Nabble.com.
> > >
> >
>

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