Two concurrent requests to the same servlet are represented in this page. The servlet is deliberately slow (1 seconds), so the two requests overlap from the same browser instance.

The first two concurrent requests from a browser to the servlet is not going to associate a session with both requests, but after a refresh both requests will be for the same session. For this test to mean something, you should do that refresh.

iframe 1: Request 1 :

iframe 2: Request 2 (concurrent with Request 1) :

After the refresh, you can make a judgement about a servlet container, by applying these rules:

Rule #Rule
1ID items colored green, may or may not be the same in requests 1 & 2
2ID items colored blue, should be the same in requests 1 & 2, otherwise concurrency issues will result
3Application and Session scoped items colored red above, should be the different in requests 1 & 2, as that is proof that an increment() happened to the same resource