Hi Team,
            I am working on a DotNetCore project and I am using the Amqp.Net Lite library to connet to MQ, I have followed steps on MQ Light messaging from Microsoft®.NET™ (Part 3) post with an intention to achieve shared subscriptions between two or more consumers, wherein I want one message to be delivered to only one consumer at a time. 
                                  My implementation works fine until a consumer takes less than 5 second to accept the message. If it takes more than 5 seconds the same message gets delivered to the other consumers. How do I stop this from happening ? 
                              

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Mahesh
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Hi Mahesh, thanks for the question. MQ uses a feature called browse-with-mark to first of all browse the new messages that need delivering to subscribers, then mark them while they are delivered. After a period of time any messages that have not been acknowledged by the subscriber are unmarked and available to deliver to other subscribers.

Messages are unmarked based on a queue-manager wide configuration attribute, MARKINT. By default the value of MARKINT is 5000 milliseconds, or 5 seconds.

If MQ Light or AMQP subscribers are likely to take longer than 5 seconds to acknowledge a message, you can modify the MARKINT attribute of the queue manager, e.g. in runmqsc:

ALTER QMGR MARKINT(10000)

Bear in mind that because the value is queue-manager wide, any other MQ applications you have that browse queues will be affected by it. If you haven't got any queue browsing applications then this shouldn't be an issue.

Hope that helps. Matt

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Matthew Whitehead
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Thanks Matthew ,
                            That really helped.

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Mahesh
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Original Message:
Sent: Mon May 18, 2020 12:03 PM
From: Matthew Whitehead
Subject: MQ Light Shared Subscription Issue

Hi Mahesh, thanks for the question. MQ uses a feature called browse-with-mark to first of all browse the new messages that need delivering to subscribers, then mark them while they are delivered. After a period of time any messages that have not been acknowledged by the subscriber are unmarked and available to deliver to other subscribers.

Messages are unmarked based on a queue-manager wide configuration attribute, MARKINT. By default the value of MARKINT is 5000 milliseconds, or 5 seconds.

If MQ Light or AMQP subscribers are likely to take longer than 5 seconds to acknowledge a message, you can modify the MARKINT attribute of the queue manager, e.g. in runmqsc:

ALTER QMGR MARKINT(10000)

Bear in mind that because the value is queue-manager wide, any other MQ applications you have that browse queues will be affected by it. If you haven't got any queue browsing applications then this shouldn't be an issue.

Hope that helps. Matt

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Matthew Whitehead
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