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Improving IBM WebSphere MQ Transport Performance

This topic is part of Guidelines for Siebel EAI Tuning.

The performance of an IBM WebSphere MQ queue is highly dependent on the disk performance of the queue manager computer and the layout of the queue's files on the disk. Test your queue with stand-alone utilities so that you have an upper boundary for the performance that can be expected in an active application.

To achieve higher throughput, consider the following options:

• Run multiple MQ Receiver tasks. Run multiple MQ Receiver tasks in parallel on the same computer or across several computers. The optimal number of MQ Receiver tasks depends on the transaction type.

  NOTE:  This guide refers to MQ Receiver, where the actual Siebel Server component you are using can be either MQSeries Server Receiver (alias MqSeriesSrvRcvr) or MQSeries AMI Receiver (alias MqSeriesAMIRcvr).

  The default number of MQ Receiver tasks is 1. You can set this to 10 or more, depending on the nature of your transactions and on available server capacity.

  Adding MQ Receivers is generally most helpful for handling CPU-bound transactions, where the dequeuing rate is low and MQ contention is not experienced.

  Sometimes contention is still experienced after adding MQ Receiver tasks, such as when multiple MQ Receivers connect to the same MQ queue manager or queue. See the next item for more information.

• Run multiple MQ queue managers. If you experience diminishing returns from adding MQ Receiver tasks, then you might benefit from running additional MQ queue managers. Doing so can help to reduce contention of MQ resources stored in physical folders on disk.
• Turn off persistent queuing if it is not necessary. Performance issues for non CPU-bound transactions or for persistent queuing are often related to MQ contention, which is not helped by adding receivers. If you do not require persistent queuing, then turn it off.

  Persistent queuing is significantly slower than normal queuing for WebSphere MQ. If you do not use this feature, however, messages will be lost if the queue manager goes down.

• Set Maximum Number of Channels parameter. Set the Maximum Number of Channels parameter in the WebSphere MQ queue manager to be greater than or equal to the maximum number of simultaneous clients you have running.

In addition, there are specific actions you can take to improve WebSphere MQ Transport performance for outbound and inbound transports, as detailed below.

Inbound Messages

For inbound WebSphere MQ messages, run multiple MQ Receivers in parallel to increase throughput.

Outbound Messages (Send, SendReceive)

Caching of WebSphere MQ Transport business services can improve outbound performance by eliminating the need to connect to the queue for each message. Caching is disabled by default because it is not usable in every situation. Follow these tips to enable caching:

• Cache in client sessions only. Do not use caching if your transport will be called within the Workflow Process Manager (WfProcMgr) component. The threading model of this component is not compatible with the WebSphere MQ APIs.
• To enable caching for a business service, set the Cache property to TRUE in Siebel Tools, then recompile the SRF file.
• If you need to call the WebSphere MQ Transport in Workflow Process Manager and in a client session, then make a separate copy of the service (one cached and one uncached) for each situation.
• Caching occurs on a per-queue basis and only one connection is kept open at a time. If a single session is going to talk to multiple queues, then consider making a copy of the transport for each outbound queue.

NOTE:  See your IBM WebSphere MQ documentation for performance and sizing guidelines.

Performance Events

You can get detailed performance tracing of the WebSphere MQ Transport by setting the EAITransportPerf event to level 5.

You can set this event level for multiple Siebel Server components that play a role in Siebel EAI functionality, including Workflow Process Manager (WfProcMgr), EAI Object Manager (EAIObjMgr), MQ Receiver, or other components. For example, you can use srvrmgr to set the event level for MQ Receiver:

change evtloglvl EAITransportPerf=5 for comp MqSeriesSrvRcvr