Source code for horovod.mxnet.functions
# Copyright 2020 Uber Technologies, Inc. All Rights Reserved.
# Modifications copyright (c) 2020, NVIDIA CORPORATION. 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.
# ==============================================================================
import io
import cloudpickle
import mxnet as mx
from horovod.mxnet.mpi_ops import allgather, broadcast_
from horovod.mxnet.mpi_ops import rank, size
[docs]def broadcast_object(obj, root_rank=0, name=None):
"""
Serializes and broadcasts an object from root rank to all other processes.
Arguments:
obj: An object capable of being serialized without losing any context.
root_rank: The rank of the process from which parameters will be
broadcasted to all other processes.
name: Optional name to use during broadcast, will default to the class
type.
Returns:
The object that was broadcast from the `root_rank`.
"""
if name is None:
name = type(obj).__name__
if rank() == root_rank:
b = io.BytesIO()
cloudpickle.dump(obj, b)
t = mx.nd.array(bytearray(b.getvalue()), dtype='byte')
sz = mx.nd.array([t.size], dtype='int')
broadcast_(sz, root_rank, name + '.sz')
else:
sz = mx.nd.empty(shape=[1], dtype='int')
broadcast_(sz, root_rank, name + '.sz')
t = mx.nd.empty(shape=[sz.asscalar()], dtype='byte')
broadcast_(t, root_rank, name + '.t')
if rank() != root_rank:
buf = io.BytesIO(t.asnumpy().tobytes())
obj = cloudpickle.load(buf)
return obj
[docs]def allgather_object(obj, name=None):
"""
Serializes and allgathers an object from all other processes.
Arguments:
obj: An object capable of being serialized without losing any context.
name: Optional name to use during allgather, will default to the class
type.
Returns:
The list of objects that were allgathered across all ranks.
"""
if name is None:
name = type(obj).__name__
def load(byte_array):
buf = io.BytesIO(byte_array.tobytes())
return cloudpickle.load(buf)
b = io.BytesIO()
cloudpickle.dump(obj, b)
t = mx.nd.array(bytearray(b.getvalue()), dtype='byte')
sz = mx.nd.array([t.size], dtype='int')
sizes = allgather(sz, name=name + '.sz').asnumpy()
gathered = allgather(t, name=name + '.t').asnumpy()
def select(i):
start = sum(sizes[:i])
end = start + sizes[i]
return gathered[start:end]
return [load(select(i)) for i in range(size())]