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Paddle/python/paddle/fluid/distributed/downpour.py

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4.5 KiB

# Copyright (c) 2018 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
from .node import DownpourServer
from .node import DownpourWorker
from ..backward import append_backward
import ps_pb2 as pslib
from paddle.fluid.distribute_lookup_table import find_distributed_lookup_table
from paddle.fluid.distribute_lookup_table import find_distributed_lookup_table_inputs
from paddle.fluid.distribute_lookup_table import find_distributed_lookup_table_outputs
from google.protobuf import text_format
class DownpourSGD(object):
"""
Distributed optimizer of downpour stochastic gradient descent
Standard implementation of Google's Downpour SGD
in Large Scale Distributed Deep Networks
Args:
learning_rate (float): the learning rate used to update parameters. \
Can be a float value
Examples:
.. code-block:: python
downpour_sgd = fluid.distributed.DownpourSGD(learning_rate=0.2)
downpour_sgd.minimize(cost)
"""
def __init__(self, learning_rate=0.001, window=1):
# todo(guru4elephant): add more optimizers here as argument
# todo(guru4elephant): make learning_rate as a variable
self.learning_rate_ = learning_rate
self.window_ = window
self.type = "downpour"
def minimize(self,
loss,
startup_program=None,
parameter_list=None,
no_grad_set=None):
"""
DownpounSGD is a distributed optimizer so
that user can call minimize to generate backward
operators and optimization operators within minmize function
Args:
loss(Variable): loss variable defined by user
startup_program(Program): startup program that defined by user
parameter_list(str list): parameter names defined by users
no_grad_set(set): a set of variables that is defined by users
so that these variables do not need gradient computation
Returns:
[ps_param, worker_skipped_ops]
ps_param: parameter server protobuf desc
worker_skipped_ops: operator names that need
to be skipped during execution
"""
params_grads = sorted(
append_backward(loss, parameter_list, no_grad_set),
key=lambda x: x[0].name)
table_name = find_distributed_lookup_table(loss.block.program)
prefetch_slots = find_distributed_lookup_table_inputs(
loss.block.program, table_name)
prefetch_slots_emb = find_distributed_lookup_table_outputs(
loss.block.program, table_name)
server = DownpourServer()
# window is communication strategy
worker = DownpourWorker(self.window_)
# Todo(guru4elephant): support multiple tables definitions
# currently support one big sparse table
sparse_table_index = 0
# currently merge all dense parameters into one dense table
dense_table_index = 1
params = []
grads = []
for i in params_grads:
params.append(i[0])
for i in params_grads:
grads.append(i[1])
server.add_sparse_table(sparse_table_index, self.learning_rate_,
prefetch_slots, prefetch_slots_emb)
server.add_dense_table(dense_table_index, self.learning_rate_, params,
grads)
worker.add_sparse_table(sparse_table_index, self.learning_rate_,
prefetch_slots, prefetch_slots_emb)
worker.add_dense_table(dense_table_index, self.learning_rate_, params,
grads)
ps_param = pslib.PSParameter()
ps_param.server_param.CopyFrom(server.get_desc())
ps_param.trainer_param.CopyFrom(worker.get_desc())
# Todo(guru4elephant): figure out how to support more sparse parameters
# currently only support lookup_table
worker_skipped_ops = ["lookup_table", "lookup_table_grad"]
ps_param.trainer_param.skip_op.extend(worker_skipped_ops)
return [ps_param, worker_skipped_ops]