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| patrick flaherty |
 Posted: Mon Apr 10, 2006 1:09 pm Post subject: Quiescing |
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Novice
Joined: 27 Mar 2006
Posts: 14
Location: SF E Bay
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Hi,
We had (for the first time) a server/listener up running over the wkend. It failed Sunday morning.
With message #2202. Which turns out to be MQRC_CONNECTION_QUIESCING.
Looked in my code (which I'd mostly copied off of various MQS-related Internet sites). This would seem pretty obvious:
| Code: |
MQOPEN (connection_handle, &object_descriptor, MQOO_INPUT_AS_Q_DEF+MQOO_FAIL_IF_QUIESCING, &object_handle, &CompCode, &Reason);
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So to fix the problem is it just a matter of removing the MQOO_FAIL_IF_QUIESCING option?
But what is Quiescing in the first place? And the code above that I'd copied, represented itself as pretty much 'default' code. So why (if so) would FAIL_IF_QUIESCING be the norm?
thanx.
pat |
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| fjb_saper |
| Posted: Mon Apr 10, 2006 1:16 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Well were you in the process of stopping the channel?
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MQ & Broker admin |
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| patrick flaherty |
| Posted: Mon Apr 10, 2006 1:27 pm Post subject: |
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Novice
Joined: 27 Mar 2006
Posts: 14
Location: SF E Bay
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From what systems, and others who can touch the MQS server machine, tell me is that they weren't doing anything.
pat |
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| patrick flaherty |
| Posted: Mon Apr 10, 2006 1:33 pm Post subject: |
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Novice
Joined: 27 Mar 2006
Posts: 14
Location: SF E Bay
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Ah. The time stamp was this morning - not Sunday.
So it was me (mea culpa).
I wanted to post a message from the Windows side without the listener (VMS [on the same Q of course]) scopping it up immediately.
(on the advice of another programmer) I right-clicking on the Channel; Stop dialog; box at the bottom = inactive.
Is there some way of 'pausing' a Q such that others applications attached to it won't die?
pat |
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| mvic |
| Posted: Mon Apr 10, 2006 1:43 pm Post subject: |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| patrick flaherty wrote: |
| Is there some way of 'pausing' a Q such that others applications attached to it won't die? |
I think the point here is that you (or someone) had said "endmqm qmgrname". When an administrator says that, the queue manager will quiesce and will end as soon as it is able to do so according to the rules outlined in the docs.
Sorry if I missed the point. |
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| kevinf2349 |
| Posted: Mon Apr 10, 2006 3:27 pm Post subject: |
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Grand Master
Joined: 28 Feb 2003
Posts: 1311
Location: USA
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| Quote: |
| So why (if so) would FAIL_IF_QUIESCING be the norm? |
It is the norm for all 'well-behaving' applications because if someone wants to stop the queue manager then the chances are they want to do it quickly. If an application detects the 'quiescing' condition then it should (if the business logic allows) get the heck out of MQ as quickly and cleanly as possible. This is particulary the case for long-running MQ enabled applications.
If they don't then the queue manager will remain up until the last application terminates. It is easier if the application detects the condition and gets out of there, than it is to manual find them and close them out.
If the application is written nicely it may even not stop, just as long as it stops its MQ activity (ie Disconnects). It could then keep on retrying the connect again every minute or so until the queue manager is back up.
Hope this helps |
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| patrick flaherty |
| Posted: Tue Apr 11, 2006 8:24 am Post subject: |
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Novice
Joined: 27 Mar 2006
Posts: 14
Location: SF E Bay
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Thanx.
But is there any way to actually pause a Q? That is, stop it from forwarding on messages (or accpeting I suppose). But nothing attached to it drops/dies/etc?
This is so the that I can inspect the contents of the current messages on the Q. This is in a development environment (as I'm rolling out a system and checking one thing after another along the way).
pat |
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| Vitor |
| Posted: Tue Apr 11, 2006 8:34 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| patrick flaherty wrote: |
Thanx.
But is there any way to actually pause a Q? That is, stop it from forwarding on messages (or accpeting I suppose). But nothing attached to it drops/dies/etc?
This is so the that I can inspect the contents of the current messages on the Q. This is in a development environment (as I'm rolling out a system and checking one thing after another along the way).
pat |
A queue doesn't forward messages; the movement of messages is controlled by the applications attached to it. It's possible to stop the placing of new messages on the queue or the removal of messages by inhibiting gets/puts but this will result in return codes and the probable termination of these applications.
The question's how the application reacts. As kevinf2349 correctly points out, polite applications don't draw attention to the foibles of the infrastructure. They cough discretely, and then retry the failing opperation. Armed with this sort of logic you can "pause" a queue by inhibiting it, examine the contents and then reenable the queue with no harm done.
Of course, if it's a development environment the same effect can be achieved by stopping and starting the applications when you want to check the queues. Fewer code changes as well, though IMHO graceful handling of errors is not a bad thing to build into prod code.
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