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2026-07-13 12:40:42 +08:00

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Python

# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import annotations
from typing import TYPE_CHECKING
from paddle.distributed.communication import stream
if TYPE_CHECKING:
from paddle import Tensor
from paddle.base.core import task
from paddle.distributed.communication.group import Group
def alltoall(
out_tensor_list: list[Tensor],
in_tensor_list: list[Tensor],
group: Group | None = None,
sync_op: bool = True,
) -> task:
"""
Scatter tensors in in_tensor_list to all participators averagely and gather the result tensors in out_tensor_list.
As shown below, the in_tensor_list in GPU0 includes 0_0 and 0_1, and GPU1 includes 1_0 and 1_1.
Through alltoall operator, the 0_0 in GPU0 will be sent to GPU0 and 0_1 to GPU1, 1_0 in GPU1 sent to GPU0 and 1_1 to GPU1.
Finally the out_tensor_list in GPU0 includes 0_0 and 1_0, and GPU1 includes 0_1 and 1_1.
.. image:: https://githubraw.cdn.bcebos.com/PaddlePaddle/docs/develop/docs/api/paddle/distributed/img/alltoall.png
:width: 800
:alt: alltoall
:align: center
Args:
out_tensor_list (List[Tensor]): List of tensors to be gathered one per rank. The data type of each tensor should be the same as the input tensors.
in_tensor_list (List[Tensor]): List of tensors to scatter one per rank. The data type of each tensor
should be float16, float32, float64, int32, int64, int8, uint8, bool or bfloat16.
group (Group, optional): The group instance return by new_group or None for global default group. Default: None.
sync_op (bool, optional): Whether this op is a sync op. The default value is True.
Returns:
Return a task object.
Examples:
.. code-block:: pycon
>>> # doctest: +REQUIRES(env: DISTRIBUTED)
>>> import paddle
>>> import paddle.distributed as dist
>>> dist.init_parallel_env()
>>> # all_to_all with equal split sizes
>>> out_tensor_list = [] # type: ignore
>>> if dist.get_rank() == 0:
... data1 = paddle.to_tensor([[1, 2, 3], [4, 5, 6]])
... data2 = paddle.to_tensor([[7, 8, 9], [10, 11, 12]])
>>> else:
... data1 = paddle.to_tensor([[13, 14, 15], [16, 17, 18]])
... data2 = paddle.to_tensor([[19, 20, 21], [22, 23, 24]])
>>> dist.alltoall(out_tensor_list, [data1, data2])
>>> print(out_tensor_list)
>>> # [[[1, 2, 3], [4, 5, 6]], [[13, 14, 15], [16, 17, 18]]] (2 GPUs, out for rank 0)
>>> # [[[7, 8, 9], [10, 11, 12]], [[19, 20, 21], [22, 23, 24]]] (2 GPUs, out for rank 1)
>>> # all_to_all with unequal split sizes
>>> if dist.get_rank() == 0:
... data1 = paddle.to_tensor([[1, 2, 3], [4, 5, 6]]) # shape: (2, 3)
... data2 = paddle.to_tensor([7]) # shape: (1, )
... out_data1 = paddle.empty((2, 3), dtype=data1.dtype)
... out_data2 = paddle.empty((3, 2), dtype=data1.dtype)
>>> else:
... data1 = paddle.to_tensor([[8, 9], [10, 11], [12, 13]]) # shape: (3, 2)
... data2 = paddle.to_tensor([[14, 15, 16, 17]]) # shape: (1, 4)
... out_data1 = paddle.empty((1,), dtype=data1.dtype)
... out_data2 = paddle.empty((1, 4), dtype=data1.dtype)
>>> dist.alltoall([out_data1, out_data2], [data1, data2])
>>> print([out_data1, out_data2])
>>> # [[[1, 2, 3], [4, 5, 6]], [[8, 9], [10, 11], [12, 13]]] (2 GPUs, out for rank 0)
>>> # [[7], [[14, 15, 16, 17]]] (2 GPUs, out for rank 1)
"""
return stream.alltoall(
out_tensor_list, in_tensor_list, group, sync_op, False
)
def alltoall_single(
out_tensor: Tensor,
in_tensor: Tensor,
in_split_sizes: list[int] | None = None,
out_split_sizes: list[int] | None = None,
group: Group | None = None,
sync_op: bool = True,
) -> task:
"""
Scatter a single input tensor to all participators and gather the received tensors in out_tensor.
Note:
``alltoall_single`` is only supported in eager mode.
Args:
out_tensor (Tensor): Output Tensor. The data type should be the same as the data type of the input Tensor.
in_tensor (Tensor): Input tensor. The data type should be float16, float32, float64, int32, int64, int8, uint8, bool or bfloat16.
in_split_sizes (list[int]|None, optional): Split sizes of ``in_tensor`` for dim[0]. If not given, dim[0] of ``in_tensor``
must be divisible by group size and ``in_tensor`` will be scattered averagely to all participators. Default: None.
out_split_sizes (list[int]|None, optional): Split sizes of ``out_tensor`` for dim[0]. If not given, dim[0] of ``out_tensor``
must be divisible by group size and ``out_tensor`` will be gathered averagely from all participators. Default: None.
group (Group|None, optional): The group instance return by ``new_group`` or None for global default group. Default: None.
sync_op (bool, optional): Whether this op is a sync op. The default value is True.
Returns:
Return a task object.
Examples:
.. code-block:: pycon
>>> # doctest: +REQUIRES(env: DISTRIBUTED)
>>> import paddle
>>> import paddle.distributed as dist
>>> dist.init_parallel_env()
>>> rank = dist.get_rank()
>>> size = dist.get_world_size()
>>> # case 1 (2 GPUs)
>>> data = paddle.arange(2, dtype='int64') + rank * 2
>>> # data for rank 0: [0, 1]
>>> # data for rank 1: [2, 3]
>>> output = paddle.empty([2], dtype='int64')
>>> dist.alltoall_single(output, data)
>>> print(output)
>>> # output for rank 0: [0, 2]
>>> # output for rank 1: [1, 3]
>>> # case 2 (2 GPUs)
>>> in_split_sizes = [i + 1 for i in range(size)]
>>> # in_split_sizes for rank 0: [1, 2]
>>> # in_split_sizes for rank 1: [1, 2]
>>> out_split_sizes = [rank + 1 for i in range(size)]
>>> # out_split_sizes for rank 0: [1, 1]
>>> # out_split_sizes for rank 1: [2, 2]
>>> data = paddle.ones([sum(in_split_sizes), size], dtype='float32') * rank
>>> # data for rank 0: [[0., 0.], [0., 0.], [0., 0.]]
>>> # data for rank 1: [[1., 1.], [1., 1.], [1., 1.]]
>>> output = paddle.empty([(rank + 1) * size, size], dtype='float32')
>>> group = dist.new_group([0, 1])
>>> task = dist.alltoall_single(
... data,
... output,
... in_split_sizes,
... out_split_sizes,
... sync_op=False,
... group=group,
... )
>>> task.wait()
>>> print(output)
>>> # output for rank 0: [[0., 0.], [1., 1.]]
>>> # output for rank 1: [[0., 0.], [0., 0.], [1., 1.], [1., 1.]]
"""
return stream.alltoall_single(
out_tensor,
in_tensor,
out_split_sizes,
in_split_sizes,
group,
sync_op,
False,
)