Method backward

extend_distributed.py:242–249

(ctx, *grad_output)

    @staticmethod
    def backward(ctx, *grad_output):
        global myreq
        for r in myreq.req:
            r.wait()
        myreq.req = None
        grad_inputs = myreq.tensor
        myreq.tensor = None
        return (None, *grad_inputs)


class All2All_ScatterList_Wait(Function):