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Date: Wed, 1 Aug 2007 01:54:25 -0700 (PDT)
From: ocoolio <adamh@freemail.hu>
To: users@activemq.apache.org
Subject: SOLUTION Re: Performance problem - On empty queue sender gets
 blocked - on filled queue it's OK
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References: <11783316.post@talk.nabble.com>


Hi everyone!

I've found out that it's a postgres concurrency bug: postgres is just bad at
concurrent transactions updating the same row/page. Switching to DB2 Express
solved it.

Cheers.


ocoolio wrote:
> 
> Hello!
> 
> I have a bad performance problem:
> 
> Im using NMS with .NET (C#) and two Qs:
> SUBMITQ
> DESTQ
> 
> A server component listens on SUBMITQ. When message received, transforms
> it and submits it to DESTQ. All done in one transaction
> (AcknowledgementMode.Transactional and sess.Commit(), PrefetchSize=1).
> This works great with stuffed queues (>10 msg pending) since the receiver
> doenst block the producer.
> The performance in this (filled q) case: ~130msg/sec on consumer.
> The producer can send about 500msg/sec.
> 
> The problem comes when the consumer empties the q. When it happens the
> producer becomes extremely slow (10msg/s) as well as the consumer. The q
> remains empty so somehow the prod and cons waits for each other.
> When I pause the consumer for a sec, the q gets a lot of messages and the
> performance is back to normal: the producer sends with 500, the consumer
> works with 130.
> 
> I use persistent messages, journal and PostgreSQL.
> Because of .NET NMS, I cannot make async sends on the client, however the
> 500/sec is just enough for me.
> 
> Please, tell me what this is, I just cannot figure it out. I dont want to
> implement wait cycles on the consumer just to get the queue packed with
> messages!
> (ActiveMQ 5.0, 2007 07 10).
> 
> Thanks,
> 
> Adam
> 

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