tensorflow参数分配策略

class _RoundRobinStrategy(object):
  """Returns the next ps task index for placement in round-robin order.

  This class is not to be used directly by users.  See instead
  `replica_device_setter()` below.
  """

  def __init__(self,num_tasks):
    """Create a new `_RoundRobinStrategy`.

    Args:
      num_tasks: Number of ps tasks to cycle among.
    """
    self._num_tasks = num_tasks
    self._next_task = 0

  def __call__(self,unused_op):
    """Choose a ps task index for the given `Operation`.

    Args:
      unused_op: An `Operation` to be placed on ps.

    Returns:
      The next ps task index to use for the `Operation`. Returns the next
      index,in the range `[offset,offset + num_tasks)`.
    """
    task = self._next_task
    self._next_task = (self._next_task + 1) % self._num_tasks
    return task

ps_strategy = _RoundRobinStrategy(ps_tasks)