Performance issues in functions/registration/multi_stage.py(P2)

[DLPerf]

Hello,I found a performance issue in functions/registration/multi_stage.py , sess = tf.Session() was repeatedly called in for i_stage, stage in enumerate and was not closed. I think it will increase the efficiency and avoid out of memory if you close this session after using it.

Here are two files to support this issue,support1 and support2

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

[hsokooti]

Hi DLPerf, thank you for your nice suggestion. Please feel free to create a PR to fix this.