OptimizeIt and AppPerfect both have a display that includes the current count of objects by class. They also have the ability to "zero out" the object counts, and display the difference between the current object counts/memory and the baseline object counts.
The information displayed is identitcal to that displayed when you take a stack dump with the HotSpot JVM with the -XX:+PrintClassHistogram option.
This kind of lightweight leak detection is very handy for our developers when trying to decide what user actions are causing leaked objects. Taking a snapshot of a 1GB process, wiggling the mouse for a big, then taking another snapshot and doing the comparison has too much overhead for our guys.
Would it be possible to add this kind of functionality to the YK telemetry view?