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| pandeg |
 Posted: Fri Mar 11, 2016 8:07 am Post subject: How to limit SVRCONN connection to 1 from JMS application |
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Disciple
Joined: 21 Oct 2014
Posts: 195
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Hi,
We have multiple JMS client applications which are connecting to Queue Manager using SVRCONN. We are seeing there the multiple count of each SVRCONN from every JMS application which is connecting to Remote Queue Manager. This is causing the Max Channel Limit to increase from default count 100. One option is to increase the Max channel limit in qm.ini. But, Can we restrict application to open more one connection instance. We have SHARECNV value set to 0. MQ version is 8.0.0.3 |
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| mqjeff |
| Posted: Fri Mar 11, 2016 8:09 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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Every MQ connection an application makes is a separate instance of the SVRCONN channel.
Any JMS application should be using some kind of connection pool that can limit the number of actual connections it makes, and reuses connections as often as possible.
The size of these connection pools should be fairly small.
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| PaulClarke |
| Posted: Fri Mar 11, 2016 8:52 am Post subject: |
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Grand Master
Joined: 17 Nov 2005
Posts: 1002
Location: New Zealand
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As well as connection pools you can also look at the MAXINST and MAXINSTC parameters on the SVRCONN channel definition. This will allow you to set limits on the maximum number of instances any one particular channel can use up of the global max channels. It can be very handy to prevent, say, a rogue applications from running away and connecting over and over again.
Having said that a Max channels of 100 is very small nowadays and most people increase it significantly. The default value of 100 was devised in the early 1990's when the computing world was a very different place and the idea of 100 Queue Managers all connected to a single central machine seemed like a lot. How times have changed. Nowadays a value of many thousands is not unusual.
Regards,
Paul.
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Paul Clarke
MQGem Software
www.mqgem.com |
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| mqjeff |
| Posted: Fri Mar 11, 2016 9:19 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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If you do implement maxinst/maxinstc... you should be prepared for developers to start whining.
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| PaulClarke |
| Posted: Fri Mar 11, 2016 9:24 am Post subject: |
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Grand Master
Joined: 17 Nov 2005
Posts: 1002
Location: New Zealand
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Doesn't that depend on what you set it to ?
After all, pretty much everything you ever do in Computing is subject to one constraint or another anyway.
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Paul Clarke
MQGem Software
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| mqjeff |
| Posted: Fri Mar 11, 2016 9:48 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| PaulClarke wrote: |
Doesn't that depend on what you set it to ?
After all, pretty much everything you ever do in Computing is subject to one constraint or another anyway. |
Sure, it does.
But if the developers are expecting to be able to create thousands, and then they can only create tens...
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| PaulClarke |
| Posted: Fri Mar 11, 2016 12:21 pm Post subject: |
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Grand Master
Joined: 17 Nov 2005
Posts: 1002
Location: New Zealand
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I'm not sure I follow your argument. Naturally one would expect the Administrator to set reasonable values for all parameters probably in consultation with Development and others.
You are surely not advocating that Administrators should just set everything to their maximum values.
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Paul Clarke
MQGem Software
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| mqjeff |
| Posted: Fri Mar 11, 2016 12:24 pm Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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No. I'm saying that developers don't tend to pay any attention to how big their thread pools *should* be, until someone comes along as says "your thread pools can't be bigger than this".
JMS in particular has been a problem in this area for a while. Developers tend to configure app server connection pools in the thousands, just because.
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| PaulClarke |
| Posted: Fri Mar 11, 2016 12:57 pm Post subject: |
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Grand Master
Joined: 17 Nov 2005
Posts: 1002
Location: New Zealand
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Ok great, sounds like we are in agreement. Developers should only be given so much rope. Especially Java programmers 
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Paul Clarke
MQGem Software
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| exerk |
| Posted: Sat Mar 12, 2016 2:36 am Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| PaulClarke wrote: |
| ...Developers should only be given so much rope. Especially Java programmers |
And a beam, and a chair... 
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It's puzzling, I don't think I've ever seen anything quite like this before...and it's hard to soar like an eagle when you're surrounded by turkeys. |
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| smdavies99 |
| Posted: Sat Mar 12, 2016 8:39 am Post subject: |
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Jedi Council
Joined: 10 Feb 2003
Posts: 6076
Location: Somewhere over the Rainbow this side of Never-never land.
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| PaulClarke wrote: |
| Ok great, sounds like we are in agreement. Developers should only be given so much rope. Especially Java programmers |
Java is a four letter word after all.
You could view ".Net' as even worse. I have to work with a GUI that is forever saying "(Not Responding)"
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Every time you reinvent the wheel the more square it gets (anon). If in doubt think and investigate before you ask silly questions. |
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| bruce2359 |
| Posted: Sat Mar 12, 2016 1:22 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9472
Location: US: west coast, almost. Otherwise, enroute.
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| PaulClarke wrote: |
| Ok great, sounds like we are in agreement. Developers should only be given so much rope. Especially Java programmers |
... and why sysadmins need to be involved in application design.
"You want to do what?!" "You want us to do what?!"
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Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| smdavies99 |
| Posted: Sun Mar 13, 2016 12:09 am Post subject: |
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Jedi Council
Joined: 10 Feb 2003
Posts: 6076
Location: Somewhere over the Rainbow this side of Never-never land.
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| bruce2359 wrote: |
| PaulClarke wrote: |
| Ok great, sounds like we are in agreement. Developers should only be given so much rope. Especially Java programmers |
... and why sysadmins need to be involved in application design.
"You want to do what?!" "You want us to do what?!" |
Or put it another way...
The answer is No. Now what is your question but the answer will still be No.
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WMQ User since 1999
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Every time you reinvent the wheel the more square it gets (anon). If in doubt think and investigate before you ask silly questions. |
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| fjb_saper |
| Posted: Sun Mar 13, 2016 9:01 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| smdavies99 wrote: |
| bruce2359 wrote: |
... and why sysadmins need to be involved in application design.
"You want to do what?!" "You want us to do what?!" |
Or put it another way...
The answer is No. Now what is your question but the answer will still be No. |
Let's be honest here. The answer is: "I'll have to think about it"... And depending on the level of knowledge of the application programmer, yes the answer might be no... 
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| bruce2359 |
| Posted: Sun Mar 13, 2016 12:13 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9472
Location: US: west coast, almost. Otherwise, enroute.
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| fjb_saper wrote: |
| smdavies99 wrote: |
| bruce2359 wrote: |
... and why sysadmins need to be involved in application design.
"You want to do what?!" "You want us to do what?!" |
Or put it another way...
The answer is No. Now what is your question but the answer will still be No. |
Let's be honest here. The answer is: "I'll have to think about it"... And depending on the level of knowledge of the application programmer, yes the answer might be no... |
"It depends."
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I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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