Writing messages to MQ on AIX using com.ibm.mq.jar - slow performance

Question

We are using WebSphere MQ client adapters on an AIX box to send messages via MQ. We send them to the outbound remote queue on the same box and find it quite slow to get to their destination - a 27mb file takes 3 minutes to run the MQQueue.put command.

Bizarrely we can change the send parameters to send to an outbound remote queue on an entirely different box and it will send the file in 2 seconds. Similarly coming back to this box from elsewhere will be quick. And sending from another box to the outbound remove queue on that same box is also slow.

So in summary the problem appears to be when sending to the outbound remote queue on the same box - we have tried specifying the destination by dns name, ip address, 127.0.0.1 etc, but no luck.

Would be grateful for any advice.

Answer 1

Try see if tcp_nodelayack makes a difference on the box. If you are at a new enough MQ level (which one are you at?) then you can just set MQ_SET_NODELAYACK to affect just MQ or alternatively (or for a quick test) just set it system wide on AIX with the 'no' command listed in the first link below.

See http://www-01.ibm.com/support/docview.wss?uid=swg21320862 FYI apar which adds the MQ specific env var option http://www-01.ibm.com/support/docview.wss?uid=swg1IZ43635

As an aside I'd also recommend trying MQ v8 client to stop MQ playing with the buffer sizes and let the o/s default them, but from the sounds of your problem I would not be surprised if the above helps.