Possible issues with max_iters when loading/saving engine's state

[vfdev-5]

Currently Engine implicitly assumes :

ignite/ignite/engine/engine.py

Line 122 in e3ef192

_state_dict_all_req_keys = ("epoch_length", "max_epochs")

but we recently introduced possibility to trigger a run with max_iters. If epoch length is unknown, saving and reloading engine's state probably wont work. We have to ensure that everything still works as expected.

@thescripted would you be interested in looking into this ?

[thescripted]

Yeah definitely, will check it out

[vfdev-5]

Thanks @thescripted !

[vfdev-5]

@thescripted could you please advance on this issue and have any updates ?