Actually the MQPUT may be dangerous if an application doing generic MQGETS
is running against the queue. Getting a specific message with a
non-existent MsgId and CorrelId should work, but to make it safer it needs
to do an MQBACK if a message is actually retrieved.
Regards
Tim A
"Potkay, Peter M
(PLC, IT)" To: [EMAIL PROTECTED]
<[EMAIL PROTECTED] cc:
RTFORD.COM> Subject: Re: Expiration Question
Sent by: MQSeries
List
<[EMAIL PROTECTED]
AC.AT>
12/03/2003 07:03
Please respond to
MQSeries List
Roger,
If the message with a CorrelId of "PGMNAME: Your dummy msg" is not
present, the app will simply go all the way thru the queue anyway, deleting
expired messages as it goes along. Isn't the put of the 1 byte message
unnecessary (not that it hurts anything; just extra)?
Peter Potkay
IBM MQSeries Certified
[EMAIL PROTECTED]
X 77906
-----Original Message-----
From: Roger Lacroix [mailto:[EMAIL PROTECTED]
Sent: Tuesday, March 11, 2003 4:16 PM
To: [EMAIL PROTECTED]
Subject: Re: Expiration Question
Hi,
Some of the platforms (i.e. OS/390) will not remove an expired message
doing
a
browse. So, I wrote a general purpose (multi-platform) C that did the
following:
- MQCONN
- MQOPEN Q for input & output
- MQPUT a 1 byte message with the following CorrelID "PGMNAME: Your dummy
msg"
- Do While RC equals 0
- MQGET by CorrelID of "PGMNAME: Your dummy msg"
- End While
- MQCLOSE Q
- MQDISC
The ONLY thing that you need to do is make sure your dummy CorrelID is
totally
unique.
I have found for cleaning up expired messages on different platforms that
putting a message with a dummy CorrelID and then doing a destructive MQGET
works every time.
later
Roger...
Quoting Jim Ford <[EMAIL PROTECTED]>:
> We've got a 'reaper' utility that we run on Solaris to take caus expired
> messages to be deleted from the queues. The utility (a Perl script)
simply
> browses through the specified queue. It accepts truncated messages, and
> uses a buffer length of 0.
>
> We've found, though, that expired messages aren't always removed. For
> example, there's one queue that gets about 20,000 messages per day, each
> with a three day expiration. When we run the expire utility in the
morning,
> we'd expect to see 20,000 messages go away on average. But it turns out
> that we were deleting just 3,000 or so, and none on some days. Eventually
> (yesterday) we hit MAXDEPTH on the queue, which was 500,000.
>
> At that time I did some investigating. I ran the utility by hand, and I
did
> some amqsbcg's againt the queue. Suddenly the queue manager decided to
> delete about 450,000 expired messages. These are persistent messages, so
> the logs were totally busy logging their deletion. That took 5 minutes
and
> the queue manager couldn't do anything else during this time.
>
> So I obviously don't fully understand the expiration process. Why doesn't
> our utility do what we expect it to do? And... what do you think I did
> yesterday that finally caused the bulk of these messages to be deleted? I
> want to make sure I don't do it again on 1st shift!
>
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