Program Hang because the Encoder without RNN

[melvinma]

I have been debugging for two days now. Please help :).

In the end, I found that if I do nothing in the encoder and just pass inputs to outputs and a fake simple state (I used zero bridge). The seq2seq run command will simply hang (process running but not doing anything). But if I added RNN call into it, it runs just fine.

What really bothers me is:
1> why I did not see any error message, even when I am in debug verbose level, I did not see any information. Could someone please let me know how to debug in this case in the future?
2> do I really need to have an RNN there?

Thanks