We already used Qlikview Server performance application but it seems that the number of session cals given by this application is different than the number gave by Qlikview Server administration console.
The concurrent session cal calculation of the QT supplied V8 app is incorrect (in my opinion). It just counts the number of sessions per hour. It does not cross hour boundries or keep track of how many sessions are in use at the same moment. I haven't checked to see if this was improved in V9.
Attached is a QVS log processor load that calculates concurrent session the way I think they should -- to the resolution of a second. That is, if two sessions share the same second in time they are concurrent. The script in the "Concurrent Sessions" script tab.
masterQVServerLogs.qvw 113.7 K