keras/src/backend/torch/optimizers/torch_parallel_optimizer.py/TorchParallelOptimizer/_backend_reset_gradient_accumulators
class TorchParallelOptimizer:    def _backend_reset_gradient_accumulators(self):
        acc_list = [v.value for v in self._accumulated_gradients]
        torch._foreach_mul_(acc_list, 0.0)