How do you collect WebSphere Average Session Size?
Assuming that you've already enabled the collection. If you haven't, then this is a snippet from our integration doc.
>When the values are always zero that is likely because they haven't added the option to enable them. From the 1st page of the WAS integration docs:
>To collect WebSphere metrics on the average size of a HTTP session, you must enable Average Size (b) Current in the Show columns list and then restart your WebSphere application server using the -Dquest.configfilter.httpsessionsize=true command.
As for the collection:
AverageSessionSize is a derived metric calculated as:
#totalSessionObjectSize# / #sessionObjectCount#
Where totalSessionObjectSize and sessionObjectCount come from the servletSessionsModule. SessionObjectSize PMI metric in WebSphere, defined as:
The size in bytes of (the serializable attributes of ) in-memory sessions. Only session objects that contain at least one serializable attribute object is counted. A session can contain some attributes that are serializable and some that are not. The size in bytes is at a session level.
We take the sum of bytes counted and the number of sessions counted from the PMI metric and report them individually, then the derived metric combines them to get an average.