What about static objects in the JVM? Would each Servlet get their own instance of X or will it get the static one?

If the Servlet spawned off threads? Then it should still work because you have not changed the TL.

Does that sound right? I was just trying to mentally think what will happen when servlet 2 comes up.

servlet1 sets the TL to "servlet1" servlet 1 creates an instance of X, say x1 while constructing x1, x1 reads TL, the read value is "servlet1" the constructor retrieves a logger whose name depends on the value of TL servlet 1 calls a method on x1, say foo() x1.foo() logs with that logger specific to the x1

servlet2 sets its TL to "servlet2" servlet2 creates an instance of X, say x2 while constructing x2, x2 reads TL, the read value is "servlet2" the constructor retrieves a logger whose name depends on the value of TL servlet2 calls a method on x2, say foo() x2.foo() logs with the logger specific to the x2

x1.foo() eventually returns servlet1 eventually returns, before returning it sets TL to null

x2.foo() eventually returns servlet2 eventually returns, before returning it sets TL to null