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I am using Red Hat JBoss AMQ 7.1.0.GA and testing flow control with producerWindowSize, I used example under amq71Install\examples\features\standard\queue, here is sample jndi.proerties:

# Neither of the following parameter works
#connectionFactory.ConnectionFactory=tcp://192.168.56.11:61616?producerWindowSize=1024
java.naming.provider.url=tcp://192.168.56.11:61616?producerWindowSize=1024

I send 10 messages with total size smaller than 1024 but still can see them arrived on broker, did I miss something or I misunderstood this parameter?

Best regards

Lan

Lan
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1 Answers1

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Yes, I believe you've misunderstood this parameter.

The "producerWindowSize" is the number of credits which the client will request from the broker. Each credit corresponds to a byte of data. When the client receives those credits then it will be able to send that number of bytes. In your case the client requests 1024 credits from the broker which it receives, therefore it is able to send 1024 bytes before requesting more credits.

Since you're sending 10 messages with a total size smaller than 1024 then you should expect them to arrive on the broker without any issue.

Justin Bertram
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  • Thanks, understood. But is it be more suitable to be configured from broker? I didn't find anything related in schema/*.xsd files. – Lan Mar 09 '18 at 02:13
  • The broker has no idea what the producerWindowSize should be for a particular client. That's up for the client to decide. However, the broker still controls the flow of credits so even though a client requests a certain amount of credits the broker doesn't have to grant them. This is based, for example, on the max-size-bytes of the address to which the producer is sending messages. If the address is over the configured max-size-bytes and the address-full-policy is BLOCK then the broker will not grant the producer any more credits. – Justin Bertram Mar 09 '18 at 14:17