Syncpoints

One of the roles of the queue manager is syncpoint control within an application. An application constructs a unit of work containing any number of MQPUT or MQGET calls terminated with an MQCMIT call. However, as the number of MQPUT or MQGET calls within the scope of one MQCMIT increases, the performance cost of the commit increases significantly.

We can limit the number of messages within any single syncpoint by using the MAXUMSGS queue manager attribute. You should not normally exceed 100 MQPUTs within a single MQCMIT.

Set a fairly low MAXUMSGS value, such as 100, to avoid performance problems, and to protect against looping applications. If you have a need for a larger value, change MAXUMSGS temporarily while the application that requires the larger value is run, rather than using a permanently high value. However, be aware that reducing the value of MAXUMSGS may cause problems to existing applications and queue manager processes such as clustering if they are already using a higher value.