Users will find 2 changes in ServiceThrottle and ServiceThrottlingBehavior classes in WinFx's JuneCTP. First is a Property name change and second is the change to some of the default values.
1. Name changes
MaxConnections renamed to MaxConcurrentSessions
MaxInstances renamed to MaxConcurrentInstances
2. Default values
MaxConcurrentSessions default reduced to 10 (Old value was 64)
MaxConcurrentCalls default reduced to 16 (Old value was 64)
The names have been changed to reflect their actual purpose and we feel is a step in the right direction. In previous CTP's when a ServiceHost was created, then that serivce by default only throttled MaxConcurrentCalls. With June CTP, the ServiceHost throttles MaxConcurrentCalls and MaxConcurrentSessions. This means that if you dont change the throttle values then your service cannot process more than 10 concurrent sessions.
To make debugging easier, we log (Logging is done at Information level) whenever the runtime pauses processing of a Message if it is unable to acquire any throttle. To prevent polluting the log with repetitive info, logging is done only when the throttling limit is exceeded by 1.
Maheshwar Jayaraman [WCF]
Update: Corrected the text in the last but one paragraph to suggest 10 concurrent sessions as opposed to 10 sessions.