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Date: Thu, 15 Jun 2006 15:04:15 +0100
From: "James Strachan" <james.strachan@gmail.com>
To: activemq-users@geronimo.apache.org
Subject: Re: limit the number of messages per second
In-Reply-To: 
 <001FD7EB9646934B9237F09DE8E1F07C02F8C147@DE0-MAILMB02.res.airbus.corp>
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References: 
 <001FD7EB9646934B9237F09DE8E1F07C02F8C147@DE0-MAILMB02.res.airbus.corp>

Is there any way you can create a test case that manages to crash the broke=
r?

On 6/15/06, Gerdes, Mike <Mike.Gerdes@airbus.com> wrote:
>
> hm I will try to use prefetch and see if it works, but mostly the problem=
 is not the consumer, but the sender and the broker having to manage everyt=
hing.
>
> The broker crashes or better it gets a deadlock. So the usagemanagers for=
 the queues request more memory and get it, at some point in time all memor=
y is used up and they request more and wait till they get it. That never ha=
ppens, because the reference co=FAnters don'T get reduced and they think th=
e queue is totally full. At that point the sender also stops and waits for =
the queue to free.
>
> I am using SSL and JAAS to allow only nodes that I trust to publish to th=
e system, but when systems get bigger a misconfiguration might occure or so=
mebody finds a trick or a way around it. It is not that critical but would =
be very nice to have.
>
> I am using AMQ4.0 the SNAPSHOT 01.05.2006. I have tried to use persistent=
 and non-persistent messages, that makes no change.
>
> I haven't found the options on how to set it, that was before you added t=
he warning and send this email, so I will try it and hope thats the problem=
.
>
>
> -----Urspr=FCngliche Nachricht-----
> Von: James Strachan [mailto:james.strachan@gmail.com]
> Gesendet: Donnerstag, 15. Juni 2006 15:45
> An: activemq-users@geronimo.apache.org
> Betreff: Re: limit the number of messages per second
>
>
>
> On 6/15/06, Gerdes, Mike <Mike.Gerdes@airbus.com> wrote:
> >
> > I want this feature to make AMQ a bit more stable, to reduce network tr=
affic and prevent flooding and to avoid that a software with errors kills m=
y system.
>
> You can use the prefetch for that...
> http://incubator.apache.org/activemq/what-is-the-prefetch-limit-for.html
>
> to limit how many messages are dispatched to a consumer.
>
>
> > From what I noticed is that AMQ does have some memory problems and that=
 it hits under certain circumstances 100 used memory and crashes then.
>
> Whats the crash? Is this the broker or client?
>
> >  But thats the smaller reason. The major reason is just for security. I=
n my testing and application I need to have a system that is more or less s=
table and secure. And DoS and flooding of queues seems to me a big problem.
>
> How about using security so only nodes you trust can publish to your queu=
es?
>
> > One thing about the memory problem, I have encountered. With more then =
one consumer and using queue, AMQ crashes with 100% used memory if I send a=
s fast as possible. This happens with and without async messages. What I no=
ticed is that the usageManagers request more and more memory and at some po=
int don't get it and then block. When a message from a queue is read, its m=
emory is not freed. With only on consumer this haven'T been the case. There=
 has the memory be freed.
> > (I put reference counter System.out.println into the usageManger)
>
> Which version of ActiveMQ are you using? Also are you using persistent
> queues? (I'm guessing not as that is not memory bound).
>
> If you are using 4.0 have you disabled optimizeAck? (see the known issues=
)
> http://incubator.apache.org/activemq/activemq-40-release.html
>
> --
>
> James
> -------
> http://radio.weblogs.com/0112098/
>
>
> This mail has originated outside your organization,
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> Keep this in mind if you answer this message.
>
> This mail has originated outside your organization, either from an extern=
al partner or the Global Internet. Keep this in mind if you answer this mes=
sage.
>


--=20

James
-------
http://radio.weblogs.com/0112098/