Performance issue in /luminoth/eval.py (by P3)

[DLPerf]

Hello! I've found a performance issue in /luminoth/eval.py: with tf.Session() as sess(here) is defined in the function evaluate_once(here) which is repeatedly called in the loop for checkpoint in checkpoints(here).

tf.Session being defined repeatedly could lead to incremental overhead. If you define tf.Session out of the loop and pass tf.Session as a parameter to the loop, your program would be much more efficient. Here is the Stack Overflow post to support it.

Looking forward to your reply. Btw, I am very glad to create a PR to fix it if you are too busy.

[DLPerf]

Hello, I'm looking forward to your reply~