The use case can be explained like this: We are doing some work based on git commits, and for each target (either commit or user defined branch name) we only want to be handling the first workload before starting the next. So we're probably going to have a high number of topics (each unique commit), but within each of those topics there might only be 1-3 messages to be handled (with the exception of the user defined branch named targets).
So we were thinking that a mq might be able to help us do this in a performant way, where our consumers are only informed of messages that are ready and valid to start (no active workload for that specific commit/branch name and it's the next within that topic). I've read the doc page you linked to about prefetch limit, could I use the prefetch limit set to 1 for topics to achieve this? man. 6. jul. 2020 kl. 18:14 skrev Domenico Francesco Bruscino < [email protected]>: > Hi Kristinn, > > the acknowledgements confirm the successful consumption of a message to the > server and generally it doesn't control directly the flow of data between > the server and the client[1]. > > Using the messaging group suitably, only one consumer will receive the > messages of a queue and if your consumer is slow you could > set consumerWindowSize to 0 (for no buffer at all)[2] to limit the > redeliveries on disconnection. > So using the messaging group and setting consumerWindowSize to 0, the > server sends all the messages of a queue to one consumer and the consumer > doesn't receive the next message before invoking the `receive()` method or > asynchronously via a message listener. > > If this solution doesn't match your requirements, the activemq-client 5 > offers a way to control the delivery with the acknowledgements using > prefetch limit [3]. > Why do you need to lock the delivery of the next message until > the acknowledgement of the previous one? > > [1] > > https://activemq.apache.org/components/artemis/documentation/latest/flow-control.html > [2] > > https://activemq.apache.org/components/artemis/documentation/latest/flow-control.html#slow-consumers > [3] https://activemq.apache.org/what-is-the-prefetch-limit-for > > Regards, > Domenico > > Il giorno lun 6 lug 2020 alle ore 09:50 Kristinn Thor Johannsson < > [email protected]> ha scritto: > > > Thanks a lot for the response Domenico. > > > > I see what I failed to mention in my original question is that each > > consumer might need a while to process a message from each queue it's > > handling. > > In your example, you had auto-acknowledge, making each message being > > instantly handled by the consumer. > > > > Is your example modifiable to make it so that a message takes about 1 > > second to be handled and acknowledged, and the consumer doesn't receive > the > > next message for the same queue before that happens? > > If so, I'm certain our use case can be handled by artemis. > > > > > > fre. 3. jul. 2020 kl. 13:02 skrev Domenico Francesco Bruscino < > > [email protected]>: > > > > > Hi Kristinn, > > > > > > I have just answered the same question on stackoverflow: > > > > > > > > > https://stackoverflow.com/questions/62701025/activemq-artemis-handle-messages-sequentially/62705413#62705413 > > > > > > Regards, > > > Domenico > > > > > > Il giorno gio 18 giu 2020 alle ore 10:51 Kristinn Thor Johannsson < > > > [email protected]> ha scritto: > > > > > > > Hi, I've tried to ensure that a consumer on a queue (with message > > > grouping) > > > > will only receive one message at a time from each queue it's > handling, > > > > until the consumer acknowledges said message. > > > > > > > > For a test I've set up ActiveMQ Artemis and have 3 consumers on a > > > wildcard > > > > EXAMPLE.* , and one publisher posting 10 messages to each of 5 > queues: > > > > EXAMPLE.1 - EXAMPLE.5 . What I'm seeing is that each of the consumers > > > > receive messages from the queues immediately. I've tried using the > > > consumer > > > > window size setting (as 0) as I thought that would help me only > deliver > > > one > > > > message at a time from each queue, but that doesn't seem to work. > Have > > I > > > > misunderstood that setting? If so, are there any other settings I > > should > > > be > > > > looking at to help me get this working? > > > > > > > > The particular use case I'm trying to achieve is that I'll possibly > > have > > > > many queues and a couple of consumers. And it's important that > messages > > > in > > > > each of the queues are handled sequentially, but all queues can be > > > handled > > > > in parallell > > > > > > > > -- > > > > -Kristinn Thor > > > > > > > > > > > > > -- > > -Kristinn Thor > > > -- -Kristinn Thor
