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| QMGR directory path being tuncated when recreating qmgr |
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| mvic |
 Posted: Tue Jun 10, 2014 11:52 am Post subject: |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| tczielke wrote: |
| What the tech note does not address is how to handle the situation when strmqm will not start because it is identifying pids that no longer exist. |
More precisely, I think the problem scenario is really the one where the pid has been re-used by the OS for a new process. So MQ is identifying that its shared memory is still in use (since it sees the pid is running on the system), when in fact it isn't in use.
| tczielke wrote: |
| It feels like there should be a strmqm option to tell MQ to remove the shared memory segments. |
That would not be "safe", for the reasons mentioned in the technote. But on the other hand, assuming the user takes responsibility for asserting to MQ that all its previously connected application pids are either ended, or have been re-used by the OS for new programs, then fair enough. |
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| fjb_saper |
| Posted: Wed Jun 11, 2014 4:48 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20696
Location: LI,NY
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| mvic wrote: |
| tczielke wrote: |
| It feels like there should be a strmqm option to tell MQ to remove the shared memory segments. |
That would not be "safe", for the reasons mentioned in the technote. But on the other hand, assuming the user takes responsibility for asserting to MQ that all its previously connected application pids are either ended, or have been re-used by the OS for new programs, then fair enough. |
Color me blind but I thought that's exactly what amqiclen did. And it could distinguish between individual qmgrs using the -m switch!
Am I missing something there? 
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| tczielke |
| Posted: Wed Jun 11, 2014 5:08 am Post subject: |
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Guardian
Joined: 08 Jul 2010
Posts: 939
Location: Illinois, USA
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To clarify, it looks like their is a use case where the administrator is somewhat left in a jam. This would be the use case where strmqm will not start because it is identifying pids in use that no longer are active. In this case, there are no applications to stop or to ask them to make a sympathetic MQI call. Also, using commands like amqiclen, ipcrm, etc. to clear any lingering shared memory segments/semaphores is discouraged by IBM due to issues it can cause to other applications that might still be using these IPC resources.
My comment about a new option for strmqm would be for strmqm to provide an option where you are basically telling MQ "clear out all the IPC resources and tell any applications that might still be connected to shared memory segements to return an appropriate error code like a broken connection and don't even attempt to access the shared memory segments if they execute a subsequent MQI call". I am sure this is incredibly simplifying what actually needs to be done from an MQ coding perpsective, but eveything involved here is IBM code (queue manager code and the MQ stub code that the application uses). |
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| mvic |
| Posted: Wed Jun 11, 2014 12:58 pm Post subject: |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| mvic wrote: |
| assuming the user takes responsibility for asserting to MQ that all its previously connected application pids are either ended, or have been re-used by the OS for new programs, then fair enough. |
| fjb_saper wrote: |
| I thought that's exactly what amqiclen did. |
Or does it? It's not documented, so who knows. |
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