| Author |
Message
|
| saneben |
 Posted: Tue Nov 20, 2007 10:49 am Post subject: Delay in processing MQ message |
 |
|
Voyager
Joined: 04 Apr 2004
Posts: 96
|
We have MQ 5.3 installed on two systems say A and B
System A put the message at 9.15 a.m and it was received successfully
on System B around 9.16 a.m as it is written on the MQ log.
But after that an external application must take the message and
process this message it processed this message at 7.30 PM. After we investigated we found n this external application was restarted at that time
The issue is we received more than 1000 messages after 9.15 a.m and all
processed the vendor of the external application is arguing that the
message was stuck in MQ
I have checked the following
1) logs - message present
2) no FDC file present
3) dead letter queue is zero
I do not have a tool to get the get time of the message so how to convince that it was an application issue and the delay was not
fromMQ.Because all the messages correctly were processed except this one. If MQ is processing in FIFO then all the messages will be stuck.
Your inputs are appreciated.
Regards |
|
| Back to top |
|
 |
| Vitor |
| Posted: Tue Nov 20, 2007 12:13 pm Post subject: Re: Delay in processing MQ message |
|
|
Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
|
| saneben wrote: |
If MQ is processing in FIFO then all the messages will be stuck.
|
Not true. MQ messages are delivered in FIFO (or FIFO within priority) true enough but messages may not get stuck. IF System B is multi-threaded (or has the ability to deal with message backlog) then there's no problem.
Consider this scenario (which I'm not sugesting has happened to you):
A message is delivered, the application reads it and tries to update a database. The database deadlocks and the application freezes. If the application is multi-threaded, or MQ detects a backlog and spins another copy of the application up, it will attempt to read the next message off the queue. This will not be one already being processed (because that's in a unit of work) so the queue will go down. The application is restarted either when the database is fixed, or to fix the database, and the message is read off and successfully processed.
Other scenarios are possible.
_________________
Honesty is the best policy.
Insanity is the best defence. |
|
| Back to top |
|
|
| JosephGramig |
| Posted: Tue Nov 20, 2007 12:17 pm Post subject: |
|
|
Grand Master
Joined: 09 Feb 2006
Posts: 1244
Location: Gold Coast of Florida, USA
|
well, FIFO or not, I doubt it was stuck. This is clearly application logic error as demonstrated by the application restart fixing the issue.
SYSTEM.DEFAULT.LOCAL.QUEUE has Priority as default, so unless you changed that about your queue, then it is Priority.
Next time they say it is stuck, check the depth of the queue.
_________________
Joseph
Administrator - IBM WebSphere MQ (WMQ) V6.0, IBM WebSphere Message Broker (WMB) V6.1 & V6.0
Solution Designer - WMQ V6.0
Solution Developer - WMB V6.1 & V6.0, WMQ V5.3 |
|
| Back to top |
|
|
| rparti |
| Posted: Tue Nov 20, 2007 1:15 pm Post subject: |
|
|
Voyager
Joined: 05 Oct 2005
Posts: 86
Location: U.S.A.
|
Find out what kind of application it is. Is it single threaded or multi-threaded.
Did the same exteral application process the 1000 messages that did not process the single message?
Was the external application restarted at 7:30 pm. or earlier/later? |
|
| Back to top |
|
|
| saneben |
| Posted: Tue Nov 20, 2007 11:51 pm Post subject: |
|
|
Voyager
Joined: 04 Apr 2004
Posts: 96
|
Reply to rparti response
Was the external application restarted at 7:30 pm. or earlier/later?
we retarted the application at 7.30 PM and immediatelt it was processed according to the application logs
Did the same exteral application process the 1000 messages that did not process the single message?
Yes the same application processed other the messages |
|
| Back to top |
|
|
| Vitor |
| Posted: Wed Nov 21, 2007 1:42 am Post subject: |
|
|
Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
|
| saneben wrote: |
| Reply to rparti response |
You didn't answer his question about single or multi-threaded. This is sounding more and more like a multi-threaded app with a problem (my and other previous posts refer).
_________________
Honesty is the best policy.
Insanity is the best defence. |
|
| Back to top |
|
|
| cwolfhagen |
| Posted: Wed Nov 21, 2007 1:48 am Post subject: Delay in processing MQ message |
|
|
Newbie
Joined: 16 Nov 2004
Posts: 8
Location: Nødebo, Denmark
|
ReQuest will be able to prove - provided the messages are put persistent - when your message arrived on the queue.
_________________
Christian Wolfhagen
Senior Consultant
Cressida Technology Ltd. |
|
| Back to top |
|
|
| saneben |
| Posted: Wed Nov 21, 2007 1:52 am Post subject: |
|
|
Voyager
Joined: 04 Apr 2004
Posts: 96
|
Hi,
I have checked with the vendor of the external application.
He confirmed that it is a multithreaded application having 10 threads.
He cannot confirm whether any thread was down as he does not have a tool.
Regards |
|
| Back to top |
|
|
| Vitor |
| Posted: Wed Nov 21, 2007 2:01 am Post subject: |
|
|
Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
|
| saneben wrote: |
| He confirmed that it is a multithreaded application having 10 threads. |
Hah!  
_________________
Honesty is the best policy.
Insanity is the best defence. |
|
| Back to top |
|
|
|
|
