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From Rob Lugt <robert.l...@cheynecapital.com>
Subject Re: Topic consumer appears throttled
Date Fri, 22 Sep 2006 20:30:05 GMT

Hi James, thanks for the quick reply.

Yes, I'm using NMS and C# for the client.  I wasn't specifying any
particular acknowledgement mode, so my previous tests would have been using
the default - but your question prompted me to try a few things out.

I found this article which describes acknowledgement modes for consumers:
http://www.activemq.org/site/activemq-performance-module-users-manual.html

I couldn't find a way to directly manipulate the consumer acknowledgement
mode using the NMS classes (if there is a way please tell me), so I used the
URI syntax on the GetTopic() method e.g. 

  IDestination destination =
session.GetTopic("PROD.PRICES.LIVE.IBM_LN?consumer.sessAckMode=autoAck");

Sorry, I don't know if I've got the syntax right, but it didn't make any
difference to the tests.  I also tried the value "dupsAck" because I read
somewhere that this could improve performance but it also didn't have any
affect.

The listener is async (delegate added to consumer.Listener) - and is very
light-weight.  I checked the CPU and memory activity on the client and the
server and both were comfortably under utilised.

Best regards
Rob Lugt


James.Strachan wrote:
> 
> This sounds like it could be related to acknowledgements - you're
> using NMS and C# as the client right? What acknowledgement mode are
> you using and are you using the async or sync listener?
> 
> On 9/22/06, Rob Lugt <robert.lugt@cheynecapital.com> wrote:
>>
>> Hi
>>
>> I'm hoping to use AMQ for a stock price publishing system, so high
>> throughput and low latency are important factors.  To verify that the
>> kind
>> of throughput we are after is achievable I've created a very simple
>> producer/consumer pair based on the sample code in
>> http://www.activemq.org/site/nms.html.
>>
>> I've come across a potential problem where the consumer's receive rate
>> dramatically falls after the number of enqueued messages exceeds a
>> certain
>> threshold.  I'm pretty sure I must be falling foul of a configuration
>> problem because the number 1000 seems to be significant.
>>
>> If the publisher sends 1000 messages, the consumer happilly receives them
>> in
>> a couple fo seconds. But, if I configure the publisher to send 1500
>> messages
>> in quick succession, I see a perculiar pattern: the consumer receives the
>> first 300 messages quickly, it then receives the next 200 messages very
>> slowly (approx 5 msgs/s) until there are exactly 1000 messages left in
>> the
>> queue and then it speeds through the last 1000 in just 2 seconds. If I
>> increase the number of messages sent, the same pattern remains i.e. the
>> consumer runs slowly until only 1000 messages remain then speeds up!
>>
>> Topology:
>>   Client 1 and Client 2 both running on a single workstation, connecting
>> via
>> OpenWire using NMS
>>   AMQ 4.0.1 Broker running on separate machine (Windows 2003 Server, J2SE
>> 1.5.0_06)
>>
>> Client 1 opens a session and publishes n (non-persistent) messages to a
>> single topic.
>> Client 2 opens a session and registers a listener on the same topic.
>>
>> I've tried various options to overcome this, none of which seem to have
>> had
>> any impact.
>> On connection uri I have:
>> jms.useAsyncSend=true&consumer.dispatchAsync=false
>> On Topic name I have: jms.useAsyncSend=true&consumer.dispatchAsync=false
>>
>> Any ideas/solutions gratefully received.
>>
>> Best regards
>> Rob Lugt
>>
>>
>>
>> --
>> View this message in context:
>> http://www.nabble.com/Topic-consumer-appears-throttled-tf2318926.html#a6451007
>> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>>
>>
> 
> 
> -- 
> 
> James
> -------
> http://radio.weblogs.com/0112098/
> 
> 

-- 
View this message in context: http://www.nabble.com/Topic-consumer-appears-throttled-tf2318926.html#a6454526
Sent from the ActiveMQ - User mailing list archive at Nabble.com.


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