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MQSeries.net Forum Index » Clustering » Question about SYNCPOINT processing.

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mqdev
PostPosted: Wed Mar 12, 2003 10:11 am    Post subject: Question about SYNCPOINT processing. Reply with quote

Centurion

Joined: 21 Jan 2003
Posts: 136
Hi,
We are faced with the following prob:
We have library which encapsulates MQGET and MQPUT functionalities. These operations are being performed under SYNCPOINT and COMMIT to satisfy certain application requirements. We need to provide different APIs to do the MQGET (under SYNPOINT) and MQCMIT operations (again a design requirement). My question is if an App does a MQGET under SYNCPOINT and then hangs (ie as far as MQSeries is concerned, the HConn and HObjs opened by that App are all valid - so MQSeries wouldn't intervene to cleanup the SYNCPOINT which it would had the App exited without commiting) without doing the MQCMIT, does it have an impact on Queue Manager (the SYNCPOINT stays in the MQ Log file and eventually the Log file rolls over - at the point that MQSeries needs to overwrite the uncommited SYNCPOINT of the earlier hanging App, the Queue Manager fails). Has anyone faced such a scenario before and if yes, how was it handled.

Thanks
mqdev
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tillywern
PostPosted: Thu Mar 20, 2003 3:45 pm    Post subject: Circular Looging? Reply with quote

Centurion

Joined: 28 Jan 2003
Posts: 109
Location: Colorado
Well if a unit of work spans all logs in a circle you will be in trouble. If your data is critical and long running then move to linear logging.

Many companies have a manditory queue manager shutdown and start durning offline hours... This has the effect of forcing applications off the queue manager...

It would be best to monitor the process doing the MQGET and ensure that it is processing messages.. If it halts then you can issue some command to remove it and the message should roll back...

I have run into situations with long running transactions, such as mq batch processing, where recovery took 8 hours because someone didn't commit regularly..

If the application is single threaded then it is easy to figure out when a halted state occurs because the queue will start to back up.... If it is multithreaded then it might be best to have each thread report when it starts its unit of work..
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