DFA parallelization

[cangozpi]

Hi, I was going through your implementation for Direct Feedback Alignement (DFA). As far as I can understand, you used register_backward_hook function to send the global error (e) to individual layers to calculate their corresponding local gradient approximations (by using backward weights, B). But does your implementation support parallelization ? I couldn't find if you supported this property of DFA algorithm. I believe using backward hooks to propagate errors works but it is still sequentially done like it was done for backpropagation so we cannot benefit from parallelization. Thank you for your time. Regards