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| poison messages |
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| Mangesh1187 |
 Posted: Wed Apr 03, 2013 10:17 am Post subject: poison messages |
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Centurion
Joined: 23 Mar 2013
Posts: 116
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Hi All,
Can any body give tell me some basic things about poision messages.
I heard the term , but dont know exactly how we can say , from many messagges, perticular message is poeion and rest of the messages are good. |
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| Vitor |
| Posted: Wed Apr 03, 2013 11:29 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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A poison message is a message which can't be processed and because of insufficient handling by whatever's reading it is just allowed to roll back onto the queue is was read from. Because WMQ supplies messages FIFO this message then becomes the next available message to be read off where it fails again for the same reason it failed the first time. The cycle repeats over and over until someone takes manual action to prevent it.
If you have a single threaded application & a queue with pure FIFO then this message will stop the reading application as all other messages will stack up behind it, hence the term "poison" because it kills your system. If you have many reading threads other messages may manage to slip past it, or a queue based on priority may see higher priority messages skip above it.
It's still a bad thing as in the best possible case you have a thread spinning round and round burning CPU and getting nowhere.
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Honesty is the best policy.
Insanity is the best defence. |
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| PeterPotkay |
| Posted: Wed Apr 03, 2013 12:02 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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And its usually the content of the message that has something wrong with it that prevents your app from processing it and moving on to the next one. Since the bogus content of the message stays the same, you spin on the message trying over and over.
If you kept MQGETing a message and rolling it back simply because your app's backend database was not available, the behavior would look the same, but you typically wouldn't refer to that message as a 'poison' message.
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Peter Potkay
Keep Calm and MQ On |
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| bruce2359 |
| Posted: Wed Apr 03, 2013 12:08 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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A poison message is a message has been consumed from a queue inside a Unit of Work, but cannot be successfully processed by the consuming application; and, as a result, is MQBACKed out back into the same queue.
An example of a poison message would be an inventory inquiry request message arriving in a payroll time-card queue. The payroll application will not be able to process the (inventory) message.
Hope this helps.
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ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| gbaddeley |
| Posted: Wed Apr 03, 2013 2:40 pm Post subject: |
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Jedi Knight
Joined: 25 Mar 2003
Posts: 2538
Location: Melbourne, Australia
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Poisoned messages can be handled using the backout count and backout queue features of MQ. When the consumer app detects that a backout count has exceeded a certain threshold, it puts the message to a backout queue and commits. This effectively removes the poisoned message from the incoming message stream. An app or human can take remedial action on the messages in the backout queue at a future time.
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Glenn |
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| Mangesh1187 |
| Posted: Wed Apr 03, 2013 11:16 pm Post subject: |
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Centurion
Joined: 23 Mar 2013
Posts: 116
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Hi All,
Thanks for your replies.
It has really given me some insight about poison messages.
I will explore more on this base knowledge.  |
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