When the global_step update?

[yuyujunjun]

In one of my projects, if I use the manual optimization, the global_step always equals to zero, and there is not any checkpoint be saved. If using the automatic optimization, everything is OK.

However, my another project advance the global_step normally even if it also uses the manual optimization.

I am very confused about the advancing way of the global_step. Could you give me any advice about fixing the bug?