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| aneelgandham |
 Posted: Wed Nov 17, 2010 12:17 pm Post subject: MaxChannels increase |
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Joined: 16 Feb 2010
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edited : voilation of policies
Last edited by aneelgandham on Mon Nov 22, 2010 6:53 am; edited 1 time in total |
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| exerk |
| Posted: Wed Nov 17, 2010 1:43 pm Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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Why were you asked to do this? What is the justification or rationale behind this decision? Those are the first two questions you should ask as the start of your analysis, and the first question I ask of you is: what does the manual state in regard to MaxChannels, and any related attributes? The second question is: have you profiled the server/queue manager to check the current resource usage at the current setting?
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| bruce2359 |
| Posted: Wed Nov 17, 2010 2:00 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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Two impacts come quickly to mind for this change:
1) a very slight (minimal, negligible) increase in memory (RAM) usage
2) the ability to have more channels
Off topic: This post brought back a moment of humor in an otherwise humorless industry.
Way back when, the bldg lights would automatically turn off at 7pm. They could be turned on manually by finding the huge switch panel (in the dark.
More and more IT folks began working evenings and nights, and wanted the lights to remain on. My mgr asked what would be the impact of having the lights on after 7pm. I replied that: 1) it would be lighter; and 2) people would likely bump into things less often.
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Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| PeterPotkay |
| Posted: Wed Nov 17, 2010 4:23 pm Post subject: |
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Poobah
Joined: 15 May 2001
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Why would there be more memory used if the MaxChannels parm was increased?
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Peter Potkay
Keep Calm and MQ On |
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| bruce2359 |
| Posted: Wed Nov 17, 2010 4:34 pm Post subject: |
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Poobah
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Location: US: west coast, almost. Otherwise, enroute.
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| Why would there be more memory used if the MaxChannels parm was increased? |
All by itself, no increase in resource consumption.
But I presupposed (there I go again) that max active would likely get to max channels...
I mean, why would someone want to lift max channels without the need for more (active) channels?
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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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| exerk |
| Posted: Wed Nov 17, 2010 10:17 pm Post subject: |
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Jedi Council
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| bruce2359 wrote: |
But I presupposed (there I go again) that max active would likely get to max channels...
I mean, why would someone want to lift max channels without the need for more (active) channels? |
You gave him the fish! That's why I obliquely referred to MaxActiveChannels as ...and any related attributes 
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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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| aneelgandham |
| Posted: Thu Nov 18, 2010 3:30 am Post subject: |
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Joined: 16 Feb 2010
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edited : violation of policies
Last edited by aneelgandham on Mon Nov 22, 2010 6:53 am; edited 1 time in total |
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| zpat |
| Posted: Thu Nov 18, 2010 3:37 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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It might be an application programming error, where they fail to disconnect from the QM in some cases.
You can use the maxinstc parameter on a svrconn channel to limit the concurrent channels from any one IP address (WMQ v7).
The first question to ask is why they think 900 is not enough? How many connections are they using per apps server. If the number is excessive for their needs, get them to reduce their pool count.
Look at MO71 channel status list (or equivalent) to see where your client connections are coming from. 900 is quite a large number already.
If the total number is regularly creeping up (especially from one server), then increasing the max channel limit will just delay the inevitable. |
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| Vitor |
| Posted: Thu Nov 18, 2010 5:10 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| aneelgandham wrote: |
| Due to an increase in the usage of websites(is wat they say), 'A' team wanted to increase the MaxChannel from 900 to 1300. This was recommended after they found the following error |
That's all very well but how did they come up with 1300? On the basis of that error you could increase it to 901 and prevent the error. Or 2000. Or 9,000. Or 13,000. Especially as they have no idea of the impact of increasing this value or they wouldn't have asked you to look into it.
I echo the comments of my associate: if the pool of connections is exhausted because the app is improperly releasing them, then no number is guaranteed to be enough.
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Insanity is the best defence. |
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| aneelgandham |
| Posted: Thu Nov 18, 2010 7:22 am Post subject: |
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edited : violation of policies
Last edited by aneelgandham on Mon Nov 22, 2010 6:55 am; edited 1 time in total |
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| fjb_saper |
| Posted: Thu Nov 18, 2010 7:26 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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You need to observe the channel over time....
Choose a day of high/max traffic.
Do the number of channel instances increase/decrease proportionally to the web traffic?
Find out your max instances, double it and use that number to evaluate what you need to set your maxchannels to.
Remember as well that if the number of channel instances does not decrease proportionally to web traffic you have a different problem and need to solve that first.
Note that the assumption here was made that your Web / App server will allow you an unrestricted number of connections in the pool. (no max pool attribute set).
Have fun 
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