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| smvineed |
 Posted: Wed Aug 17, 2016 1:54 am Post subject: purpose of subpool.lck file |
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Apprentice
Joined: 24 Jul 2011
Posts: 34
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Could you please explain the use of subpool.lck in /var/mqm/sockets/XXX/qmgrlocal/hostname?
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| mqjeff |
| Posted: Wed Aug 17, 2016 3:48 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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It's a lock file.
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| Vitor |
| Posted: Wed Aug 17, 2016 4:24 am Post subject: Re: purpose of subpool.lck file |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| smvineed wrote: |
| Could you please explain the use of subpool.lck in /var/mqm/sockets/XXX/qmgrlocal/hostname? |
It's nothing you should be worrying about or fiddling with.
It belongs to the software and you shouldn't be playing with its toys.
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| bruce2359 |
| Posted: Wed Aug 17, 2016 1:09 pm Post subject: Re: purpose of subpool.lck file |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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| smvineed wrote: |
| Could you please explain the use of subpool.lck in /var/mqm/sockets/XXX/qmgrlocal/hostname? |
A general explanation follows:
Locks are used in multi-user (server) software to provide serialized access to important resources - in this instance virtual storage. A subpool is an area of virtual storage reserved for some specific purpose - for example: holding database rows, or messages in queues.
The contents of a subpool may require that it is only accessed by one "user" at a time. The subpool lock must first be acquired before the resource it protects can be accessed.
For MQ queues, some users may be browsing messages, others may be destructively consuming messages. Some mechanism must be in place to ensure that no two (or more) concurrent users are trying to destructively consume the same message at the same time. Locks provide this mechanism.
As it relates to IP network traffic, the socket() calls read or write into buffers (subpools). To keep multiple listeners writers from overwriting IP packets as they sit in buffers, the buffers are protected by locks.
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| gbaddeley |
| Posted: Wed Aug 17, 2016 5:41 pm Post subject: |
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Jedi Knight
Joined: 25 Mar 2003
Posts: 2538
Location: Melbourne, Australia
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I have experienced MQ FixPack installation failures like:
"Verifying selections...You seem to have an MQ queue manager still running. You must stop all MQ processing, and stop the Queue Manager(s) by using the endmqm command before trying to install/update/delete the MQ product."
There was no actual qmgr running at the time. The solution is to remove the subpool.lck file:
rm /var/mqm/sockets/<qmgr name>/qmgrlocl/<hostname>/subpool.lck
A new file is created when the qmgr starts. This is the only interaction I have ever had with this file over 20 years of MQ tech support.
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| mqjeff |
| Posted: Thu Aug 18, 2016 3:33 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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gbaddeley - Is it in any way possible that either some MQ process was still running, or had ended/crashed badly?
I know that in general you would not fail to check these things, but one always has those days...
Particularly when one hasn't had enough coffee... yes, Vitor?
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| Vitor |
| Posted: Thu Aug 18, 2016 6:00 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| mqjeff wrote: |
gbaddeley - Is it in any way possible that either some MQ process was still running, or had ended/crashed badly?
I know that in general you would not fail to check these things, but one always has those days...
Particularly when one hasn't had enough coffee... yes, Vitor? |
   
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| gbaddeley |
| Posted: Thu Aug 18, 2016 5:53 pm Post subject: |
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Jedi Knight
Joined: 25 Mar 2003
Posts: 2538
Location: Melbourne, Australia
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| mqjeff wrote: |
| gbaddeley - Is it in any way possible that either some MQ process was still running, or had ended/crashed badly? |
There were no mqm processes running, dspmq showed the qmgr as ended normally, running amqiclen did not help.
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| mqjeff |
| Posted: Fri Aug 19, 2016 3:49 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| gbaddeley wrote: |
| mqjeff wrote: |
| gbaddeley - Is it in any way possible that either some MQ process was still running, or had ended/crashed badly? |
There were no mqm processes running, dspmq showed the qmgr as ended normally, running amqiclen did not help. |
As I said, I know in general that you would check these things. Seems very odd, though, that this file would still exist. I could speculate on several reasons, but I don't think that's terribly productive at this point, and the coffee hasn't kicked in yet.
I'd still not recommend that *anyone* muck with this file outside the scope of a PMR.
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| smvineed |
| Posted: Fri Aug 19, 2016 4:06 am Post subject: purpose of subpool.lck file |
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Apprentice
Joined: 24 Jul 2011
Posts: 34
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Thank you all for the explanations 
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