IBM Websphere MQ: MAXHANDS queue manager parameter - Middleware News

What is the purpose of the MAXHANDS queue manager parameter?

MAXHANDS (Maximum Open Handles) is the queue manager parameter that limits the number of handles that any one process can have at the same time. The details relating to it are as follows:

Setting MAXHANDS:

• Alter the MAXHANDS queue manager parameter using the MQSC alter queue manager command. Example: alter qmgr maxhands (300)
• On Windows you can also use the WebSphere MQ Explorer to alter the queue manager's Max handles, extended property.

MAXHANDS(integer):
The maximum number of open handles that any one task can have at the same time. This is a value in the range zero through 999 999 999.

For clarification:
MAXHANDS refers to the maximum number of objects that a single connection can have open at the same time. So, if an application thread issues an MQOPEN for a queue, that counts as 1, and so on for each queue that is opened in that thread. A separate thread in the same or in a different process also has its own MAXHANDLES objects that it can open. The total number of handles for a queue, for example the number of applications that have a queue open, is not related to MAXHANDLES.

The open handles for a queue can be displayed using the display queue status command. In the example below, the qstatus for a queue named 3 shows that there are three open handles on the queue. The open handles are owned by PIDs 1928, 2572 and 2504.



For further details refer to the online topics regarding the MAXHANDS queue manager parameter, and the display qstatus command.