MQSeries.net :: View topic - Multithreading with TimeoutControl/TimeoutNotification Retry

howardl · Posted: Fri Aug 19, 2011 9:06 am Post subject:

I am using a TimeoutControl node and TimeoutNotification node as a retry mechanism for a SOAP Request. The time for the synchronous response from the web service combined with TimeoutNotifications only having one instance is not allowing the throughput I am looking for. I am looking to be able to increase the capacity of the web service delivery flow with multiple threads while still taking advantage of the Timeout nodes.

I have found having a separate flow to only put the timeout event to a queue and then let the web service delivery flow take input from the queue allows the multiple threads for delivery I want. While solving the multithreading on delivery issue, it introduces the risk of duplicate messages if the queue gets backed up to the point where the delay is greater than the retry interval.

I have a few options to stop this duplicate messages problem, but my questions are what are the pros/cons/risks associated with each option, are there any other options for the duplicate messages problem or any other multithreading options in general, and is this a possible risk/bad idea in general to try to introduce multithreading while using timeout control?

Option 1: When the message is put to the queue set an expiry slightly less than the retry interval. If the message sits on the queue for too long the message will expire before the duplicate message gets put on the queue. However, it is possible for this to repeat until the retry count runs out, and then the last message expires and the message never delivers when it may of been possible too.

Option 2: Before putting the message to the delivery queue perform a mqget to determine if the message already exists. This would require a second queue in the middle though, as a mqget directly in the TimeoutNotification flow once again introduces the delay with a single thread problem.