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| amq6150, semaphore in Aix |
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| jeevan |
 Posted: Sun Nov 22, 2009 2:35 pm Post subject: amq6150, semaphore in Aix |
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Grand Master
Joined: 12 Nov 2005
Posts: 1432
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My new project has MQ on Aix. I have worked with AIX way before. One thing different with MQ on AIX was semaphore. But I have a one confustion which I could not clear with the help of google.
My understand was that even the queue manager is shutdown cleanly, we need to clear the semaphore manually. The infocentre does not tell this explicitely.
http://publib.boulder.ibm.com/infocenter/wmqv6/v6r0/index.jsp
My colleage thinks that if the queue manager shuts down cleanly, the semaphore is cleared but I think it does not. Could someone help me to understand what happens. |
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| exerk |
| Posted: Sun Nov 22, 2009 4:02 pm Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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They should be cleared automatically on clean shut-down...if not, there's something wrong.
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| jeevan |
| Posted: Sun Nov 22, 2009 4:30 pm Post subject: |
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Grand Master
Joined: 12 Nov 2005
Posts: 1432
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| exerk wrote: |
| They should be cleared automatically on clean shut-down...if not, there's something wrong. |
Does that mean, if the queue manager is shutdown gracefully( endmqm qmgr), then there would not come an issues of IPC(semaphore).
Also, from the following( taken from the above link), it seems that, even the semaphore was not cleared, that will get cleared while restarting the queue manager. Does that mean we should not worry about semaphore at all?
| Quote: |
When a WebSphere MQ queue manager is ended normally, the queue manager removes the majority of the IPC resources that it was using. A small number of IPC resources remain and this is as designed: some of the IPC resources are intended to persist between queue manager restarts. The number of IPC resources remaining varies to some extent, depending on the operating conditions.
There are some situations when a larger proportion of the IPC resources in use by a queue manager might persist after that queue manager has ended:
If applications are connected to the queue manager when it stops (perhaps because the queue manager was shut down using endmqm -i or endmqm -p), the IPC resources used by these applications might not be released.
If the queue manager ends abnormally (for example, if an operator issues the system kill command), some IPC resources might be left allocated after all queue manager processes have terminated.
In these cases, the IPC resources are not released back to the system until you restart (strmqm) or delete (dltmqm) the queue manager.
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| bruce2359 |
| Posted: Sun Nov 22, 2009 7:50 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9470
Location: US: west coast, almost. Otherwise, enroute.
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| Quote: |
| Does that mean, if the queue manager is shutdown gracefully( endmqm qmgr), then there would not come an issues of IPC (semaphore) |
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The paragraph you quoted did not say that all semaphores would be released. Rather, it said (or implied) that some semaphores might not be released. As the paragraph implies, it depends. The paragraph did not offer all that much detail, did it?
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| fjb_saper |
| Posted: Sun Nov 22, 2009 9:23 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Remember as well to help you manage IPC resources AFTER qmgr shutdown you may use amqiclen...
I tend to only use it for upgrades. After having shutdown all qmgrs on the box I clear the memory used by MQ using amqiclen... I could as well have the system admin use ipcrm, but it is easier to have amqiclen identify the ipc resources and release them. 
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| gbaddeley |
| Posted: Sun Nov 22, 2009 10:42 pm Post subject: |
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Jedi Knight
Joined: 25 Mar 2003
Posts: 2538
Location: Melbourne, Australia
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| fjb_saper wrote: |
Remember as well to help you manage IPC resources AFTER qmgr shutdown you may use amqiclen...
I tend to only use it for upgrades. After having shutdown all qmgrs on the box I clear the memory used by MQ using amqiclen... I could as well have the system admin use ipcrm, but it is easier to have amqiclen identify the ipc resources and release them. |
Yeah, there is really no need to worry about IPC resources, unless you are doing an upgrade, or the queue manager terminated abnormally, or processes were killed.
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| jeevan |
| Posted: Mon Nov 23, 2009 5:43 am Post subject: |
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Grand Master
Joined: 12 Nov 2005
Posts: 1432
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| bruce2359 wrote: |
| Quote: |
| Does that mean, if the queue manager is shutdown gracefully( endmqm qmgr), then there would not come an issues of IPC (semaphore) |
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The paragraph you quoted did not say that all semaphores would be released. Rather, it said (or implied) that some semaphores might not be released. As the paragraph implies, it depends. The paragraph did not offer all that much detail, did it? |
Yes, I agree that the paragraphs do not tell t hat. but it tellls that
| Quote: |
In these cases, the IPC resources are not released back to the system until you restart (strmqm) or delete (dltmqm) the queue manager
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My point is that if these unreleased resources will be released when we restart the queue manager why should we need to worry? In other words, if they are going to released anyway, we do not need to worry for manual intervention. Should we?
But as fjb-saper said, if we are going to do upgrade, we need to take care of it before we upgrade. |
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| Vitor |
| Posted: Mon Nov 23, 2009 6:22 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| jeevan wrote: |
| My point is that if these unreleased resources will be released when we restart the queue manager why should we need to worry? In other words, if they are going to released anyway, we do not need to worry for manual intervention. Should we? |
If you don't intend to restart that queue manager for a period of time (possibly because it's hosted on a multi-use box and the use has changed) then you might want the resources back.
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| bruce2359 |
| Posted: Mon Nov 23, 2009 6:41 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9470
Location: US: west coast, almost. Otherwise, enroute.
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| Quote: |
| ...if they are going to released anyway, we do not need to worry for manual intervention. Should we? |
The paragraph you quoted did not say that the semaphores are going to be released anyway.
The stranded semaphores issue is not just an MQ issue.
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Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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