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MQSeries.net Forum Index » General IBM MQ Support » Active logs running behind ?

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thimerion
PostPosted: Mon Nov 19, 2007 2:53 am    Post subject: Active logs running behind ? Reply with quote

Acolyte

Joined: 08 May 2007
Posts: 67
Location: Belgium

Hi,

We did use following procedure to proof to the customer that we did/didn't receive a certain queue message.

Take a copy of the active logs
Look for an unique number in the contents of the file
If we find it in there, then we received it, else we did not.

Recently we found a situation that we did not find the file in the active logs, but when we did it again an hour later, we did find the file in there.

So the question is, are the active logs not immediately written after a message is received? Is there a delay in writing active logs, and where does it come from?



Regards,
Tim
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Vitor
PostPosted: Mon Nov 19, 2007 2:58 am    Post subject: Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA

You don't mention what platform you're running on. It's possible the opperating system is doing buffered writes, or some other low level function is preventing you seeing the message.

IMHO it's not an ideal way of checking for message delivery. I'd use some of the software facilities to prove this, assuming you can't (as you should) rely on the assured deliver. Note that the method will fail completly for non-persistent messages, which are not logged.
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thimerion
PostPosted: Mon Nov 19, 2007 3:12 am    Post subject: persistent on windows Reply with quote

Acolyte

Joined: 08 May 2007
Posts: 67
Location: Belgium

Hi,
We are talking about a windows 2003 server and all messages are persistent.

Tim
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Vitor
PostPosted: Mon Nov 19, 2007 3:22 am    Post subject: Re: persistent on windows Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA

thimerion wrote:
We are talking about a windows 2003 server and all messages are persistent.


Well I'm not aware of any specific buffered write facility on Win2003 but there could be, or the messages could be in the swap file waiting to be written, or it could just be Windoze doing it's normal tricks.

Do you actually know it took an hour for the message to show in the log; i.e. did you look, not see it, check an hour later and see it or check every 5 mins for 60 mins and then see it?

I still think it's a bad way to check for message arrival. Escpecially now you've proved you can't rely on it!
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thimerion
PostPosted: Mon Nov 19, 2007 3:29 am    Post subject: hour Reply with quote

Acolyte

Joined: 08 May 2007
Posts: 67
Location: Belgium

No it's not exacty an hour, I incidently checked an hour later and the message was there, so it could be any interval from 0-60 minutes when the message was written.

I agree on your point checking the active logs is a bad way to proof a message was arrived. But when there is no message on your dead queue, and the customer has no message on the dead queue, but claims to have send it. Where could it be gone ... so the active logs are a bit of a last resort then.

That message I talk about above, I did never find. Therefor I did check with some other messages and discovered the delayed write.

One remark about the lost message, the queue manager was restarted at the time the message arrived, but in my opinion that should not lead to data loss.
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Vitor
PostPosted: Mon Nov 19, 2007 3:36 am    Post subject: Re: hour Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA

thimerion wrote:
No it's not exacty an hour, I incidently checked an hour later and the message was there, so it could be any interval from 0-60 minutes when the message was written.


So it could have been there 5 seconds later.

thimerion wrote:
But when there is no message on your dead queue, and the customer has no message on the dead queue, but claims to have send it. Where could it be gone


If I got money each time I was told a message was "lost" I'd have retired years ago. In my personal experience the vast majority of these very common cases are resolved when the customer's claim to have sent it is refuted. In one very extreme case, when challenged to prove they'd sent the message, the customer triumpantly produced an application log segment which proved they'd put the message "because the put came back with code - 2085".

If you face a lot of this, build proper auditing into the system.
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Michael Dag
PostPosted: Mon Nov 19, 2007 3:44 am    Post subject: Re: hour Reply with quote

Jedi Knight

Joined: 13 Jun 2002
Posts: 2607
Location: The Netherlands (Amsterdam)

thimerion wrote:
No it's not exacty an hour, I incidently checked an hour later and the message was there, so it could be any interval from 0-60 minutes when the message was written.

what's the timeout value of your channels? default is 1800 secs = 30 minutes.
I have not seen delays in writing, but use short timeout values, so a channel closes within 5 minutes of no traffic.
thimerion wrote:

I agree on your point checking the active logs is a bad way to proof a message was arrived. But when there is no message on your dead queue, and the customer has no message on the dead queue, but claims to have send it. Where could it be gone ...

The application reading the message?
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Vitor
PostPosted: Mon Nov 19, 2007 4:20 am    Post subject: Re: hour Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
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Michael Dag wrote:
The application reading the message?


The 2nd most popular explaination after it not being sent in the 1st place.....
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fjb_saper
PostPosted: Mon Nov 19, 2007 4:26 am    Post subject: Reply with quote

Grand High Poobah

Joined: 18 Nov 2003
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How about the reading app discarding the message but not keeping record of discarded messages... because after all the reading app makes no mistakes... and only "good" messages are being logged...
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Vitor
PostPosted: Mon Nov 19, 2007 4:56 am    Post subject: Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
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Location: Texas, USA

fjb_saper wrote:
... because after all the reading app makes no mistakes...


Your site has one of those as well? An infallable application?
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thimerion
PostPosted: Mon Nov 19, 2007 5:16 am    Post subject: sending app - reading app Reply with quote

Acolyte

Joined: 08 May 2007
Posts: 67
Location: Belgium

Hi,

The sending app is not under our management, so can't comment on that.

I also don't want to state that our reading app is fawlessly, that would be egocentric.

The reading app never saw the message, at least that's what we see in it's output logs.

We'll start with asking the logs of the sending app to the customer.

About the timeout value of the channel, I only see values like Disconnect interval, heartbeat interval ... what is the exact parameter name?

Tim
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Vitor
PostPosted: Mon Nov 19, 2007 5:26 am    Post subject: Re: sending app - reading app Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA

thimerion wrote:
I also don't want to state that our reading app is fawlessly, that would be egocentric.


Why not? Everyone else seems to state that, why should you miss out.....????
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Michael Dag
PostPosted: Mon Nov 19, 2007 5:39 am    Post subject: Reply with quote

Jedi Knight

Joined: 13 Jun 2002
Posts: 2607
Location: The Netherlands (Amsterdam)

disconnect interval (it's in seconds)
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thimerion
PostPosted: Mon Nov 19, 2007 5:44 am    Post subject: disconnect interval Reply with quote

Acolyte

Joined: 08 May 2007
Posts: 67
Location: Belgium

Disconnect interval = 6000
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