There's nothing pretty. The QMgr does not have capability to limit the GET
rate so either the consumers are aware of each other's state or some
outboard process intercepts the messages on a pre-queue and feeds them into
the real queue at a pre-determined rate.
One approach that I have seen is to maintain a token queue with a certain
number of messages in it. In a single transaction, the app acquires a
message from the token queue and puts it back in the same queue without
committing. The app then does it's normal processing on the main queue -
get a message, execute the back-end transaction, COMMIT. This allows the
app to have an unlimited number of consumers from many remote servers but
limits the simultaneous transactions to however many messages are in the
token queue. The content of the messages in the token queue doesn't matter,
however I've found that if the app writes some identifying information then
tracing I/O on the queue reveals valuable diagnostics as to load
distribution and app health.
It's not a perfect solution since it isn't time based, but has the advantage
of not requiring much awareness of the different app instances to one
another and therefore minimal code changes. It also allows many more
consumers than can possibly be run at once so you know the queue will always
be served, so long as one instance remains. And it's tunable. Need to run
faster? Add a message or two to the token queue. Need to throttle back?
Delete a message or two.
-- T.Rob
-----Original Message-----
Behalf Of AkBar Dar
Sent: Sunday, July 14, 2013 2:29 PM
Subject: Re: Throttle MQ Messages
Rob
You understood correctly, I am trying to research a solution that is other
DataPower, if not then I got no choice to go with DataPower.
Regards,
AkBar Dar
Telecommute Day: Wednesday
________________________________________
From: MQSeries List on behalf of T.Rob
Sent: Sunday, July 14, 2013 2:15:35 PM
Subject: Re: Throttle MQ Messages
Hi AkBar,
Not sure I understand the objective. WMQ will get the messages as far
down the pipe as possible as fast as possible. Is it the delivery of
messages
to the queue that you wish throttled, or the delivery of messages from the
queue to the consumer(s)?
One common problem is that a queue served by many consumers results in
all those consumers hitting the same back-end application. If the
consumers can generate more traffic than the back-end can handle, that
usually means there are too many consumers. This would be indicated if,
for example, the back end having problems was a database.
However, if the back end system is driven by a web service, the load
shaping can be done by DataPower or similar. For example, 20 consumers
all try to hit the same web service which is configured for no more than
10
requests per second. The DataPower box simply discards 10 of the
requests. The apps driving the transactions roll back their messages on
the
queue and loop around to try again. The 20 requests are spread over 2 or
three seconds instead of one.
Or did I completely misunderstand the question?
-- T.Rob
-----Original Message-----
On
Behalf Of AkBar Dar
Sent: Sunday, July 14, 2013 1:34 PM
Subject: Throttle MQ Messages
Is there to way in MQ to Read messages in a batch? I want to throttle
the pick up of the messages off the Queue so that back end Application
is not overwhelmed. I know there is way in Message Broker version 10.
But, I am working with MQ 6 and Broker 6.
Please advise.
Regards,
AkBar Dar
Telecommute Day: Wednesday
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