Just to be clear for when I look at it...were you using trunk or 0.12 for those tests, and presumably you were calling commit after your simulated processing delay?
Robbie On 28 October 2011 00:28, Praveen M <[email protected]> wrote: > Hi Robbie, > > I was using asynchronous onMessage delivery with transacted session for my > tests. > > So from your email, I'm afraid it might be an issue. It will be great if you > could investigate a little on this and keep us update. > > Thanks a lot, > Praveen > > On Thu, Oct 27, 2011 at 11:49 AM, Robbie Gemmell > <[email protected]>wrote: > >> From the below, would I be right in thinking you were using receive() >> calls with an AutoAck session? If so then you would see the behaviour >> you observed as the message gets acked just before receive() returns, >> which makes the broker send the next one to the client. That shouldnt >> happen if you were using asynchronous onMessage delivery (since the >> ack gets since when the onMessage() handler returns), or if you you >> used a ClientAck or Transacted session in which you only acknowledged >> the message / commited the session after the processing is complete. >> >> I must admit to having never used the client with prefetch set to 0, >> which should in theory give you what you are looking for even with >> AutoAck but based on your comments appears not to have. I will try and >> take a look into that at the weekend to see if there are any obvious >> issues we can JIRA for fixing. >> >> Robbie >> >> On 26 October 2011 23:48, Praveen M <[email protected]> wrote: >> > Hi Jakub, >> > >> > Thanks for your reply. Yes I did find the prefetch model and reran my >> test >> > and now ran into another issue. >> > >> > I set the prefetch to 1 and ran the same test described in my earlier >> mail. >> > >> > In this case the behavior I see is, >> > The 1st consumer gets the 1st message and works on it for a while, the >> 2nd >> > consumer consumes 8 messages and then does nothing(even though there was >> 1 >> > more unconsumed message). When the first consumer completed its long >> running >> > message it got around and consumed the remaining 1 message. However, I >> was >> > expecting the 2nd consumer to dequeue all 9 messages(the number of >> remaining >> > messages) while the 1st consumer was busy working on the long message. >> > >> > Then, I thought, perhaps the prefetch count meant that, when a consumer >> is >> > working on a message, another message in the queue is prefetched to the >> > consumer from the persistant store as my prefetch count is 1. That could >> > explain why I saw the behavior as above. >> > >> > What i wanted to achieve was to actually turn of any kinda prefetching >> > (Yeah, I'm ok with taking the throughput hit) >> > >> > So I re ran my test now with prefetch = 0, and saw a really weird result. >> > >> > With prefetch 0, the 1st consumer gets the 1st message and works on it >> for a >> > while, which the 2nd consumer consumes 7 messages(why 7?) and then does >> > nothing(even though there were 2 more unconsumed messages). When the 1st >> > consumer completed processing it's message it got to consume the >> remaining >> > two messages too. (Did it kinda prefetch 2?) >> > >> > Can someone please tell me if Is this a bug or am I doing something >> > completely wrong? I'm using the latest Java Broker & client (from trunk) >> > with DerbyMessageStore for my tests. >> > >> > Also, can someone please tell me what'd be the best way to turn off >> > prefetching? >> > >> > Thanks a lot, >> > Praveen >> > >> > >> > On Wed, Oct 26, 2011 at 3:45 AM, Jakub Scholz <[email protected]> wrote: >> > >> >> Hi Praveen, >> >> >> >> Have you set the capacity / prefetch for the receivers to one message? >> >> I believe the capacity defines how many messages can be "buffered" by >> >> the client API in background while you are still processing the first >> >> message. That may cause that both your clients receive 5 messages, >> >> even when the processing in the first client takes a longer time. >> >> >> >> Regards >> >> Jakub >> >> >> >> On Wed, Oct 26, 2011 at 03:02, Praveen M <[email protected]> >> wrote: >> >> > Hi, >> >> > >> >> > I ran the following test >> >> > >> >> > 1) I created 1 Queue >> >> > 2) Registered 2 consumers to the queue >> >> > 3) Enqueued 10 messages to the Queue. [ The first enqueued message is >> >> long >> >> > running. I simulated such that the first message on consumption takes >> >> about >> >> > 50 seconds to be processed] >> >> > 4) Once the enqueue is committed, the 2 consumers each pick a message. >> >> > 5) The 1st consumer that got the long running message works on it for >> a >> >> long >> >> > time while the second consumer that got the second message keeps >> >> processing >> >> > and going to the next message, but only goes as far until it >> processes 5 >> >> of >> >> > the 10 messages enqueued. Then the 2nd consumer gives up processing. >> >> > 6) When the 1st consumer with the long running message completes, it >> >> then >> >> > ends up processing the remaining messages and my test completes. >> >> > >> >> > So it seems like the two consumers were trying to take a fair share of >> >> > messages that they were processing immaterial of the time it takes to >> >> > process individual messages. Enqueued message = 10, Consumer 1 share >> of 5 >> >> > messages were processed by it, and Consumer 2's share of 5 messages >> were >> >> > processed by it. >> >> > >> >> > >> >> > This is kinda against the behavior that I'd like to see. The desired >> >> > behavior in my case is that of each consumer keeps going on if it's >> done >> >> and >> >> > has other messages to process. >> >> > >> >> > In the above test, I'd expect as consumer 1 is working on the long >> >> message, >> >> > the second consumer should work its way through all the remaining >> >> messages. >> >> > >> >> > Is there some config that I'm missing that could cause this effect?? >> Any >> >> > advice on tackling this will be great. >> >> > >> >> > Also, Can someone please explain in what order are messages delivered >> to >> >> the >> >> > consumers in the following cases? >> >> > >> >> > Case 1) >> >> > There is a single Queue with more than 1 message in it and multiple >> >> > consumers registered to it. >> >> > >> >> > Case 2) >> >> > There are multiple queues each with more than 1 message in it, and has >> >> > multiple consumers registered to it. >> >> > >> >> > >> >> > >> >> > Thank you, >> >> > -- >> >> > -Praveen >> >> > >> >> >> >> --------------------------------------------------------------------- >> >> Apache Qpid - AMQP Messaging Implementation >> >> Project: http://qpid.apache.org >> >> Use/Interact: mailto:[email protected] >> >> >> >> >> > >> > >> > -- >> > -Praveen >> > >> >> --------------------------------------------------------------------- >> Apache Qpid - AMQP Messaging Implementation >> Project: http://qpid.apache.org >> Use/Interact: mailto:[email protected] >> >> > > > -- > -Praveen > --------------------------------------------------------------------- Apache Qpid - AMQP Messaging Implementation Project: http://qpid.apache.org Use/Interact: mailto:[email protected]
