When and how one can set a random seed for Chainer

I cannot find any guarantee on how to set a random seed to make Chainer deterministic. I want Chainer to clarify when and how it is deterministic.

numpy.random.seed and cupy.random.seed may work, but there seems no guarantee that Chainer has no other random sources, and I can find some exceptions: cudnn, atomicAdd (https://groups.google.com/forum/#!topic/chainer-jp/JN9H9aF4TA8), https://github.com/chainer/chainer/blob/master/chainer/datasets/sub_dataset.py, https://github.com/chainer/chainer/blob/master/chainer/functions/connection/n_step_rnn.py.

[kmaehashi]

We discussed offline:

• We need to document how to make Chainer computation deterministic.
• We need system to show warnings for non-deterministic computations, e.g.,
  • introduce decorator (like @chainer.non_deterministic) to annotate known non-deterministic functions (e.g., using atomicAdd)
  • introduce configuration option (like chainer.config.check_deterministic)
  • if the configuration is True and the function with the annotation is invoked, raise warning.

[Crissman]

After discussion, we’ve decided that the PRs done covers the issue of flagging code which is non-deterministic, and cannot be given a seed. Closing this issue.