File size: 7,432 Bytes
97b6013
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
# Copyright 2018 The TensorFlow 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.
# ==============================================================================
"""Helper functions for running models in a distributed setting."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import json
import os
import random
import string

from absl import logging
import tensorflow.compat.v2 as tf

from official.utils.misc import tpu_lib


def _collective_communication(all_reduce_alg):
  """Return a CollectiveCommunication based on all_reduce_alg.

  Args:
    all_reduce_alg: a string specifying which collective communication to pick,
      or None.

  Returns:
    tf.distribute.experimental.CollectiveCommunication object

  Raises:
    ValueError: if `all_reduce_alg` not in [None, "ring", "nccl"]
  """
  collective_communication_options = {
      None: tf.distribute.experimental.CollectiveCommunication.AUTO,
      "ring": tf.distribute.experimental.CollectiveCommunication.RING,
      "nccl": tf.distribute.experimental.CollectiveCommunication.NCCL
  }
  if all_reduce_alg not in collective_communication_options:
    raise ValueError(
        "When used with `multi_worker_mirrored`, valid values for "
        "all_reduce_alg are [`ring`, `nccl`].  Supplied value: {}".format(
            all_reduce_alg))
  return collective_communication_options[all_reduce_alg]


def _mirrored_cross_device_ops(all_reduce_alg, num_packs):
  """Return a CrossDeviceOps based on all_reduce_alg and num_packs.

  Args:
    all_reduce_alg: a string specifying which cross device op to pick, or None.
    num_packs: an integer specifying number of packs for the cross device op.

  Returns:
    tf.distribute.CrossDeviceOps object or None.

  Raises:
    ValueError: if `all_reduce_alg` not in [None, "nccl", "hierarchical_copy"].
  """
  if all_reduce_alg is None:
    return None
  mirrored_all_reduce_options = {
      "nccl": tf.distribute.NcclAllReduce,
      "hierarchical_copy": tf.distribute.HierarchicalCopyAllReduce
  }
  if all_reduce_alg not in mirrored_all_reduce_options:
    raise ValueError(
        "When used with `mirrored`, valid values for all_reduce_alg are "
        "[`nccl`, `hierarchical_copy`].  Supplied value: {}".format(
            all_reduce_alg))
  cross_device_ops_class = mirrored_all_reduce_options[all_reduce_alg]
  return cross_device_ops_class(num_packs=num_packs)


def get_distribution_strategy(distribution_strategy="mirrored",
                              num_gpus=0,
                              all_reduce_alg=None,
                              num_packs=1,
                              tpu_address=None):
  """Return a DistributionStrategy for running the model.

  Args:
    distribution_strategy: a string specifying which distribution strategy to
      use. Accepted values are "off", "one_device", "mirrored",
      "parameter_server", "multi_worker_mirrored", and "tpu" -- case insensitive.
      "off" means not to use Distribution Strategy; "tpu" means to use
      TPUStrategy using `tpu_address`.
    num_gpus: Number of GPUs to run this model.
    all_reduce_alg: Optional. Specifies which algorithm to use when performing
      all-reduce. For `MirroredStrategy`, valid values are "nccl" and
      "hierarchical_copy". For `MultiWorkerMirroredStrategy`, valid values are
      "ring" and "nccl".  If None, DistributionStrategy will choose based on
      device topology.
    num_packs: Optional.  Sets the `num_packs` in `tf.distribute.NcclAllReduce`
      or `tf.distribute.HierarchicalCopyAllReduce` for `MirroredStrategy`.
    tpu_address: Optional. String that represents TPU to connect to. Must not
      be None if `distribution_strategy` is set to `tpu`.
  Returns:
    tf.distribute.DistibutionStrategy object.
  Raises:
    ValueError: if `distribution_strategy` is "off" or "one_device" and
      `num_gpus` is larger than 1; or `num_gpus` is negative or if
      `distribution_strategy` is `tpu` but `tpu_address` is not specified.
  """
  if num_gpus < 0:
    raise ValueError("`num_gpus` can not be negative.")

  distribution_strategy = distribution_strategy.lower()
  if distribution_strategy == "off":
    if num_gpus > 1:
      raise ValueError(
          "When {} GPUs are specified, distribution_strategy "
          "flag cannot be set to `off`.".format(num_gpus))
    return None

  if distribution_strategy == "tpu":
    # When tpu_address is an empty string, we communicate with local TPUs.
    cluster_resolver = tpu_lib.tpu_initialize(tpu_address)
    return tf.distribute.experimental.TPUStrategy(cluster_resolver)

  if distribution_strategy == "multi_worker_mirrored":
    return tf.distribute.experimental.MultiWorkerMirroredStrategy(
        communication=_collective_communication(all_reduce_alg))

  if distribution_strategy == "one_device":
    if num_gpus == 0:
      return tf.distribute.OneDeviceStrategy("device:CPU:0")
    if num_gpus > 1:
      raise ValueError("`OneDeviceStrategy` can not be used for more than "
                       "one device.")
    return tf.distribute.OneDeviceStrategy("device:GPU:0")

  if distribution_strategy == "mirrored":
    if num_gpus == 0:
      devices = ["device:CPU:0"]
    else:
      devices = ["device:GPU:%d" % i for i in range(num_gpus)]
    return tf.distribute.MirroredStrategy(
        devices=devices,
        cross_device_ops=_mirrored_cross_device_ops(all_reduce_alg, num_packs))

  if distribution_strategy == "parameter_server":
    return tf.distribute.experimental.ParameterServerStrategy()

  raise ValueError(
      "Unrecognized Distribution Strategy: %r" % distribution_strategy)


def configure_cluster(worker_hosts=None, task_index=-1):
  """Set multi-worker cluster spec in TF_CONFIG environment variable.

  Args:
    worker_hosts: comma-separated list of worker ip:port pairs.

  Returns:
    Number of workers in the cluster.
  """
  tf_config = json.loads(os.environ.get("TF_CONFIG", "{}"))
  if tf_config:
    num_workers = (len(tf_config["cluster"].get("chief", [])) +
                   len(tf_config["cluster"].get("worker", [])))
  elif worker_hosts:
    workers = worker_hosts.split(",")
    num_workers = len(workers)
    if num_workers > 1 and task_index < 0:
      raise ValueError("Must specify task_index when number of workers > 1")
    task_index = 0 if num_workers == 1 else task_index
    os.environ["TF_CONFIG"] = json.dumps({
        "cluster": {
            "worker": workers
        },
        "task": {"type": "worker", "index": task_index}
    })
  else:
    num_workers = 1
  return num_workers


def get_strategy_scope(strategy):
  if strategy:
    strategy_scope = strategy.scope()
  else:
    strategy_scope = DummyContextManager()

  return strategy_scope


class DummyContextManager(object):

  def __enter__(self):
    pass

  def __exit__(self, *args):
    pass