问题
We are trying to connect to IBMMQ using CCDT file and JMS configuration. We are able to connect to it but we have an issue here:
since we are using spring to set connection factory with CCDT file, this is initialized once at the start of the application, but unfortunately it picks only one queue manager at a time,i.e it sends all the messages to same queue manager and it does not load balance.
Though i observed, if i manually set the CCDT file before every request then its able to load balance the Queue Managers, ideally it looks to me Queue Manager is decided whenever i set the URL to CCDT file. which is wrong practice. My expectation was to initialize the connection factory with CCDT file and then this configuration will be able to load balance on its own.
Can you help me this?
回答1:
This is the expected behavior. MQ does not load balance clients, it connection balances them. The connection is the single most time consuming API call and in the case of a mutually authenticated TLS connection can take seconds to complete. Therefore a good application design will attempt to connect once, then maintain that connection for the duration of the session. The JMS architecture and Spring framework both expect this pattern.
The way that MQ provides load distribution (again, not true balancing, but rather round-robin distribution) is that the client connects a hop away from a clustered destination queue. A message addressed to that clustered destination queue will round-robin among all the instances of that queue.
If it is a request-reply application, the thing listening for requests on these clustered queue instances addresses the reply message using the Reply-To QMgr and Reply-To Queue name from the requesting message. In this scenario the requestors can fail over QMgr to QMgr if they lose their connection. The systems of record listening on the clustered queues generally do not fail over across queue managers in order to ensure all queue instances are served and because of transaction recovery.
Short answer is that CCDT and MQ client in general are not where MQ load distribution occurs. The client should make a connection and hold it as long as possible. Client reconnect and CCDT are for connection balancing only.
Load distribution is a feature of the MQ cluster. It requires multiple instances of a clustered queue and these are normally a network hop away from the client app that puts the message.
来源：https://stackoverflow.com/questions/48404838/load-balancing-issue-while-connecting-to-ibm-mq-using-jms-ccdt-file