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| mnair77 |
 Posted: Tue May 20, 2014 10:52 am Post subject: Time lag before requeue |
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Newbie
Joined: 02 Oct 2013
Posts: 4
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Hi,
WMB 8.0.0.2, MQ 7.5
I am observing a time lag between a message rollback and the message getting re-read as part of retry processing. The following user trace snapshot shows the issue. The input node is MQInput.
| Code: |
2014-05-20 11:13:15.059193 5780 UserException BIP2951I: Event generated by user code. Additional information : ''out of range'' 'TestFlow.Compute' '{2}' '{3}' '{4}' '{5}' '{6}' '{7}' '{8}' '{9}'
The event was generated by an SQL LOG or THROW statement. This is the normal behavior of these statements.
Since this is a user generated event, the user action is determined by the message flow and the type of event.
2014-05-20 11:13:15.059212 5780 UserTrace BIP11507W: Rolled back a local transaction.
A local transaction has been rolled back for work done on the message flow thread.
2014-05-20 11:13:16.098134 5780 UserTrace BIP11501I: Received data from input node ''MQ Input''.
The input node ''MQ Input'' has received data and has propagated it to the message flow ''TestFlow''.
2014-05-20 11:13:16.098674 5780 Error BIP2648E: Message backed out to a queue; node 'TestFlow.MQ Input'.
Node 'TestFlow.MQ Input' has received a message which has previously been backed out one or more times because of a processing error in the main path of the message flow. The failure terminal is not attached, so the message broker is putting the message directly to the requeue or dead letter backout queue associated with this node. The MQMD 'backoutCount' of the message now equals the 'backoutThreshold' defined for the WebSphere MQ input queue.
Examine previous messages and the message flow to determine why the message is being backed out. Correct this situation if possible. Perform any local error recovery processing required.
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Note the delay of nearly 1 second between the exception and requeue. This test was with no catch/failure connections. If I connect the catch terminal and re-throw, I see the 1-second delay before failure terminal processing as well as message getting backed out, leading to total processing time of 2+ seconds. What could be the reason for this delay?
EDIT: I didn't realize this went to the wrong forum. Moderator, Kindly move to Message Broker support. |
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| mnair77 |
| Posted: Mon Jun 30, 2014 12:10 pm Post subject: |
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Newbie
Joined: 02 Oct 2013
Posts: 4
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I had opened a PMR for this issue. The response from IBM is that there is a hardcoded delay of 1 second in the rollback processing in WMB. There is no way to avoid it if you're depending on broker's rollback.
To work around this, I modified my exception handling subflow to end with an MQOutput instead of a Throw node, to explicitly commit messages into my backout queue. |
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| McueMart |
| Posted: Tue Jul 01, 2014 12:58 am Post subject: |
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Chevalier
Joined: 29 Nov 2011
Posts: 490
Location: UK...somewhere
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Yes I had also spoken to development about this and was informed of this hardcoded delay of 1s.
In my opinion this is a defect as it should be at least be a configurable value. I believe the intention of the 1s delay is to prevent poison messages causing 100% CPU utilisation. But it has the knock on effect that when your flows are encountering exceptions, it rate-limits the flow to 1 tps (causing massive message backlogs - I would prefer all the messages to be processed fast and processed by our exception handling process!)
I wonder if as part of your PMR you could request that this value be made configurable? |
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| PeterPotkay |
| Posted: Tue Jul 01, 2014 3:09 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| McueMart wrote: |
| I wonder if as part of your PMR you could request that this value be made configurable? |
If someone submitted this as a Request For Enhancement and shared the link on this forum, it would probably get a lot of votes. That's the best way to initiate change in the product.
http://www.ibm.com/developerworks/rfe/
_________________
Peter Potkay
Keep Calm and MQ On |
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| mnair77 |
| Posted: Tue Jul 01, 2014 3:13 pm Post subject: |
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Newbie
Joined: 02 Oct 2013
Posts: 4
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| fjb_saper |
| Posted: Tue Jul 01, 2014 6:40 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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If you are using the developer edition you're limited to 1 tps anyway... 
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MQ & Broker admin |
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