[HACKYSTAT-DEV-L:253] BUG: All our selectors are thread-unsafe

[(Cedric) Qin ZHANG]

Hi, Philip,
In the telemetry viewer for 413, I need to run the same analyses for 
different projects. So multiple requests are send at the same time:

Request1: do analysis for Project AAA
Request2: do analysis for Porject BBB
....
One the server side, the ProjectSelector.afterCommandReceivedHook() will 
store the last selected project by calling:
  user.put("selector.ProjectDefault", lastSelectedProjectName)

Then (still on the server side), the analysis needs to find out what the 
project the user has selected by calling
  ProjectSelector.getSelectedProject()
which in turn calls
  user.get("selector.ProjectDefault").

Now think what might happen when two requests are sent at the same time.
  Request1: user.put("selector.ProjectDefault", "AAA")
  Request2: user.put("selector.ProjectDefault", "BBB")
  Request1: user.get("selector.ProjectDefault") returns "BBB"
  Request2: user.get("selector.ProjectDefault") returns "BBB"
But what request1 has requested is "AAA".
I have two solutions for the problem:
  (1) put the last selected project information in thread local storage.
  (2) put it in user session.
Since all our selector follow the same pattern, they are all unsafe.
Telemetry wall is ready, but if this bug cannot get fixed before 
Wednesday, it cannot be used.

Sincerely,
Cedric