[Deploying Sakai] Measuring session size

[Matthew Buckett]

Does anyone have any good idea about Sakai session size on the heap.
We're considering increasing our session timeout from 2 hours but
would like to have an idea about the impact of this on our heap usage.
I've had a quick go at using sizeof
(https://github.com/dweiss/java-sizeof) but it seems that our object
tree is huge, most likely because something in the session holds a
reference to a spring service, and once you've got a reference to one
of them you can walk the object graph to almost all the others. Better
sizeof allows filtering of the objects you walk but I couldn't manage
to get this to easily filter out all the services from the objects
walked.

Looking at a heap dump would give us an idea but we our currently out
of term time so it may not be a very good indicator.


Side note:
- There's been some good discussion about session size on:
https://jira.sakaiproject.org/browse/SAK-25677

-- 
  Matthew Buckett, VLE Developer, IT Services, University of Oxford