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DeepSpeech.py
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DeepSpeech.py
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
from __future__ import absolute_import, division, print_function
import os
import sys
log_level_index = sys.argv.index('--log_level') + 1 if '--log_level' in sys.argv else 0
os.environ['TF_CPP_MIN_LOG_LEVEL'] = sys.argv[log_level_index] if log_level_index > 0 and log_level_index < len(sys.argv) else '3'
import datetime
import pickle
import shutil
import six
import subprocess
import tensorflow as tf
import time
import traceback
import inspect
from six.moves import zip, range, filter, urllib, BaseHTTPServer
from tensorflow.python.tools import freeze_graph
from threading import Thread, Lock
from util.audio import audiofile_to_input_vector
from util.bngru import BNGRUCell
from util.feeding import DataSet, ModelFeeder
from util.gpu import get_available_gpus
from util.shared_lib import check_cupti
from util.text import sparse_tensor_value_to_texts, wer, levenshtein, Alphabet, ndarray_to_text
from xdg import BaseDirectory as xdg
import numpy as np
# Importer
# ========
tf.app.flags.DEFINE_string ('train_files', '', 'comma separated list of files specifying the dataset used for training. multiple files will get merged')
tf.app.flags.DEFINE_string ('dev_files', '', 'comma separated list of files specifying the dataset used for validation. multiple files will get merged')
tf.app.flags.DEFINE_string ('test_files', '', 'comma separated list of files specifying the dataset used for testing. multiple files will get merged')
tf.app.flags.DEFINE_boolean ('fulltrace', False, 'if full trace debug info should be generated during training')
# Cluster configuration
# =====================
tf.app.flags.DEFINE_string ('ps_hosts', '', 'parameter servers - comma separated list of hostname:port pairs')
tf.app.flags.DEFINE_string ('worker_hosts', '', 'workers - comma separated list of hostname:port pairs')
tf.app.flags.DEFINE_string ('job_name', 'localhost', 'job name - one of localhost (default), worker, ps')
tf.app.flags.DEFINE_integer ('task_index', 0, 'index of task within the job - worker with index 0 will be the chief')
tf.app.flags.DEFINE_integer ('replicas', -1, 'total number of replicas - if negative, its absolute value is multiplied by the number of workers')
tf.app.flags.DEFINE_integer ('replicas_to_agg', -1, 'number of replicas to aggregate - if negative, its absolute value is multiplied by the number of workers')
tf.app.flags.DEFINE_integer ('coord_retries', 100, 'number of tries of workers connecting to training coordinator before failing')
tf.app.flags.DEFINE_string ('coord_host', 'localhost', 'coordination server host')
tf.app.flags.DEFINE_integer ('coord_port', 2500, 'coordination server port')
tf.app.flags.DEFINE_integer ('iters_per_worker', 1, 'number of train or inference iterations per worker before results are sent back to coordinator')
# Global Constants
# ================
tf.app.flags.DEFINE_boolean ('train', True, 'whether to train the network')
tf.app.flags.DEFINE_boolean ('test', True, 'whether to test the network')
tf.app.flags.DEFINE_integer ('epoch', 75, 'target epoch to train - if negative, the absolute number of additional epochs will be trained')
tf.app.flags.DEFINE_boolean ('use_warpctc', False, 'whether to use GPU bound Warp-CTC')
tf.app.flags.DEFINE_float ('dropout_rate', 0.05, 'dropout rate for feedforward layers')
tf.app.flags.DEFINE_float ('dropout_rate2', -1.0, 'dropout rate for layer 2 - defaults to dropout_rate')
tf.app.flags.DEFINE_float ('dropout_rate3', -1.0, 'dropout rate for layer 3 - defaults to dropout_rate')
tf.app.flags.DEFINE_float ('dropout_rate4', 0.0, 'dropout rate for layer 4 - defaults to 0.0')
tf.app.flags.DEFINE_float ('dropout_rate5', 0.0, 'dropout rate for layer 5 - defaults to 0.0')
tf.app.flags.DEFINE_float ('dropout_rate6', -1.0, 'dropout rate for layer 6 - defaults to dropout_rate')
tf.app.flags.DEFINE_float ('relu_clip', 20.0, 'ReLU clipping value for non-recurrant layers')
# DS2 parameters
tf.app.flags.DEFINE_float ('decay', 0.99, 'decay parameter of the Batch Normalization layers')
tf.app.flags.DEFINE_integer ('kernel_size', 11, 'the size of the kernel in the convolutional layers')
tf.app.flags.DEFINE_integer ('stride', 2, 'the stride of the convolutional layers')
tf.app.flags.DEFINE_integer ('recurrent_layers', 5, 'the number of recurrent layers')
# Adam optimizer (http://arxiv.org/abs/1412.6980) parameters
tf.app.flags.DEFINE_float ('beta1', 0.9, 'beta 1 parameter of Adam optimizer')
tf.app.flags.DEFINE_float ('beta2', 0.999, 'beta 2 parameter of Adam optimizer')
tf.app.flags.DEFINE_float ('epsilon', 1e-8, 'epsilon parameter of Adam optimizer')
tf.app.flags.DEFINE_float ('learning_rate', 0.001, 'learning rate of Adam optimizer')
# Batch sizes
tf.app.flags.DEFINE_integer ('train_batch_size', 1, 'number of elements in a training batch')
tf.app.flags.DEFINE_integer ('dev_batch_size', 1, 'number of elements in a validation batch')
tf.app.flags.DEFINE_integer ('test_batch_size', 1, 'number of elements in a test batch')
# Sample limits
tf.app.flags.DEFINE_integer ('limit_train', 0, 'maximum number of elements to use from train set - 0 means no limit')
tf.app.flags.DEFINE_integer ('limit_dev', 0, 'maximum number of elements to use from validation set- 0 means no limit')
tf.app.flags.DEFINE_integer ('limit_test', 0, 'maximum number of elements to use from test set- 0 means no limit')
# Step widths
tf.app.flags.DEFINE_integer ('display_step', 0, 'number of epochs we cycle through before displaying detailed progress - 0 means no progress display')
tf.app.flags.DEFINE_integer ('validation_step', 0, 'number of epochs we cycle through before validating the model - a detailed progress report is dependent on "--display_step" - 0 means no validation steps')
# Checkpointing
tf.app.flags.DEFINE_string ('checkpoint_dir', '', 'directory in which checkpoints are stored - defaults to directory "deepspeech/checkpoints" within user\'s data home specified by the XDG Base Directory Specification')
tf.app.flags.DEFINE_integer ('checkpoint_secs', 600, 'checkpoint saving interval in seconds')
tf.app.flags.DEFINE_integer ('max_to_keep', 5, 'number of checkpoint files to keep - default value is 5')
# Exporting
tf.app.flags.DEFINE_string ('export_dir', '', 'directory in which exported models are stored - if omitted, the model won\'t get exported')
tf.app.flags.DEFINE_integer ('export_version', 1, 'version number of the exported model')
tf.app.flags.DEFINE_boolean ('remove_export', False, 'whether to remove old exported models')
tf.app.flags.DEFINE_boolean ('use_seq_length', True, 'have sequence_length in the exported graph (will make tfcompile unhappy)')
# Reporting
tf.app.flags.DEFINE_integer ('log_level', 1, 'log level for console logs - 0: INFO, 1: WARN, 2: ERROR, 3: FATAL')
tf.app.flags.DEFINE_boolean ('log_traffic', False, 'log cluster transaction and traffic information during debug logging')
tf.app.flags.DEFINE_string ('wer_log_pattern', '', 'pattern for machine readable global logging of WER progress; has to contain %%s, %%s and %%f for the set name, the date and the float respectively; example: "GLOBAL LOG: logwer(\'12ade231\', %%s, %%s, %%f)" would result in some entry like "GLOBAL LOG: logwer(\'12ade231\', \'train\', \'2017-05-18T03:09:48-0700\', 0.05)"; if omitted (default), there will be no logging')
tf.app.flags.DEFINE_boolean ('log_placement', False, 'whether to log device placement of the operators to the console')
tf.app.flags.DEFINE_integer ('report_count', 10, 'number of phrases with lowest WER (best matching) to print out during a WER report')
tf.app.flags.DEFINE_string ('summary_dir', '', 'target directory for TensorBoard summaries - defaults to directory "deepspeech/summaries" within user\'s data home specified by the XDG Base Directory Specification')
tf.app.flags.DEFINE_integer ('summary_secs', 0, 'interval in seconds for saving TensorBoard summaries - if 0, no summaries will be written')
# Geometry
tf.app.flags.DEFINE_integer ('n_hidden', 2048, 'layer width to use when initialising layers')
# Initialization
tf.app.flags.DEFINE_integer ('random_seed', 4567, 'default random seed that is used to initialize variables')
tf.app.flags.DEFINE_float ('default_stddev', 0.046875, 'default standard deviation to use when initialising weights and biases')
# Early Stopping
tf.app.flags.DEFINE_boolean ('early_stop', True, 'enable early stopping mechanism over validation dataset. Make sure that dev FLAG is enabled for this to work')
# This parameter is irrespective of the time taken by single epoch to complete and checkpoint saving intervals.
# It is possible that early stopping is triggered far after the best checkpoint is already replaced by checkpoint saving interval mechanism.
# One has to align the parameters (earlystop_nsteps, checkpoint_secs) accordingly as per the time taken by an epoch on different datasets.
tf.app.flags.DEFINE_integer ('earlystop_nsteps', 4, 'number of steps to consider for early stopping. Loss is not stored in the checkpoint so when checkpoint is revived it starts the loss calculation from start at that point')
tf.app.flags.DEFINE_float ('estop_mean_thresh', 0.5, 'mean threshold for loss to determine the condition if early stopping is required')
tf.app.flags.DEFINE_float ('estop_std_thresh', 0.5, 'standard deviation threshold for loss to determine the condition if early stopping is required')
# Decoder
tf.app.flags.DEFINE_string ('decoder_library_path', 'native_client/libctc_decoder_with_kenlm.so', 'path to the libctc_decoder_with_kenlm.so library containing the decoder implementation.')
tf.app.flags.DEFINE_string ('alphabet_config_path', 'data/alphabet.txt', 'path to the configuration file specifying the alphabet used by the network. See the comment in data/alphabet.txt for a description of the format.')
tf.app.flags.DEFINE_string ('lm_binary_path', 'data/lm/lm.binary', 'path to the language model binary file created with KenLM')
tf.app.flags.DEFINE_string ('lm_trie_path', 'data/lm/trie', 'path to the language model trie file created with native_client/generate_trie')
tf.app.flags.DEFINE_integer ('beam_width', 1024, 'beam width used in the CTC decoder when building candidate transcriptions')
tf.app.flags.DEFINE_float ('lm_weight', 1.75, 'the alpha hyperparameter of the CTC decoder. Language Model weight.')
tf.app.flags.DEFINE_float ('word_count_weight', 1.00, 'the beta hyperparameter of the CTC decoder. Word insertion weight (penalty).')
tf.app.flags.DEFINE_float ('valid_word_count_weight', 1.00, 'valid word insertion weight. This is used to lessen the word insertion penalty when the inserted word is part of the vocabulary.')
# Inference mode
tf.app.flags.DEFINE_string ('one_shot_infer', '', 'one-shot inference mode: specify a wav file and the script will load the checkpoint and perform inference on it. Disables training, testing and exporting.')
# Initialize from frozen model
tf.app.flags.DEFINE_string ('initialize_from_frozen_model', '', 'path to frozen model to initialize from. This behaves like a checkpoint, loading the weights from the frozen model and starting training with those weights. The optimizer parameters aren\'t restored, so remember to adjust the learning rate.')
for var in ['b1', 'h1', 'b2', 'h2', 'b3', 'h3', 'b5', 'h5', 'b6', 'h6']:
tf.app.flags.DEFINE_float('%s_stddev' % var, None, 'standard deviation to use when initialising %s' % var)
FLAGS = tf.app.flags.FLAGS
def initialize_globals():
# ps and worker hosts required for p2p cluster setup
FLAGS.ps_hosts = list(filter(len, FLAGS.ps_hosts.split(',')))
FLAGS.worker_hosts = list(filter(len, FLAGS.worker_hosts.split(',')))
# Determine, if we are the chief worker
global is_chief
is_chief = len(FLAGS.worker_hosts) == 0 or (FLAGS.task_index == 0 and FLAGS.job_name == 'worker')
# Initializing and starting the training coordinator
global COORD
COORD = TrainingCoordinator()
COORD.start()
# The absolute number of computing nodes - regardless of cluster or single mode
global num_workers
num_workers = max(1, len(FLAGS.worker_hosts))
# Create a cluster from the parameter server and worker hosts.
global cluster
cluster = tf.train.ClusterSpec({'ps': FLAGS.ps_hosts, 'worker': FLAGS.worker_hosts})
# If replica numbers are negative, we multiply their absolute values with the number of workers
if FLAGS.replicas < 0:
FLAGS.replicas = num_workers * -FLAGS.replicas
if FLAGS.replicas_to_agg < 0:
FLAGS.replicas_to_agg = num_workers * -FLAGS.replicas_to_agg
# The device path base for this node
global worker_device
worker_device = '/job:%s/task:%d' % (FLAGS.job_name, FLAGS.task_index)
# This node's CPU device
global cpu_device
cpu_device = worker_device + '/cpu:0'
# This node's available GPU devices
global available_devices
available_devices = [worker_device + gpu for gpu in get_available_gpus()]
# If there is no GPU available, we fall back to CPU based operation
if 0 == len(available_devices):
available_devices = [cpu_device]
# Set default dropout rates
if FLAGS.dropout_rate2 < 0:
FLAGS.dropout_rate2 = FLAGS.dropout_rate
if FLAGS.dropout_rate3 < 0:
FLAGS.dropout_rate3 = FLAGS.dropout_rate
if FLAGS.dropout_rate6 < 0:
FLAGS.dropout_rate6 = FLAGS.dropout_rate
global dropout_rates
dropout_rates = [ FLAGS.dropout_rate,
FLAGS.dropout_rate2,
FLAGS.dropout_rate3,
FLAGS.dropout_rate4,
FLAGS.dropout_rate5,
FLAGS.dropout_rate6 ]
global no_dropout
no_dropout = [ 0.0 ] * 6
# Set default checkpoint dir
if len(FLAGS.checkpoint_dir) == 0:
FLAGS.checkpoint_dir = xdg.save_data_path(os.path.join('deepspeech','checkpoints'))
# Set default summary dir
if len(FLAGS.summary_dir) == 0:
FLAGS.summary_dir = xdg.save_data_path(os.path.join('deepspeech','summaries'))
# Standard session configuration that'll be used for all new sessions.
global session_config
session_config = tf.ConfigProto(allow_soft_placement=True, log_device_placement=FLAGS.log_placement)
global alphabet
alphabet = Alphabet(os.path.abspath(FLAGS.alphabet_config_path))
# Geometric Constants
# ===================
# For an explanation of the meaning of the geometric constants, please refer to
# doc/Geometry.md
# Number of MFCC features
global n_input
n_input = 26 # TODO: Determine this programatically from the sample rate
# The number of frames in the context
global n_context
n_context = 9 # TODO: Determine the optimal value using a validation data set
# Number of units in hidden layers
global n_hidden
n_hidden = FLAGS.n_hidden
global n_hidden_1
n_hidden_1 = n_hidden
global n_hidden_2
n_hidden_2 = n_hidden
global n_hidden_5
n_hidden_5 = n_hidden
# LSTM cell state dimension
global n_cell_dim
n_cell_dim = n_hidden
# The number of units in the third layer, which feeds in to the LSTM
global n_hidden_3
n_hidden_3 = 2 * n_cell_dim
# The number of characters in the target language plus one
global n_character
n_character = alphabet.size() + 1 # +1 for CTC blank label
# The number of units in the sixth layer
global n_hidden_6
n_hidden_6 = n_character
# Assign default values for standard deviation
for var in ['b1', 'h1', 'b2', 'h2', 'b3', 'h3', 'b5', 'h5', 'b6', 'h6']:
val = getattr(FLAGS, '%s_stddev' % var)
if val is None:
setattr(FLAGS, '%s_stddev' % var, FLAGS.default_stddev)
# Queues that are used to gracefully stop parameter servers.
# Each queue stands for one ps. A finishing worker sends a token to each queue before joining/quitting.
# Each ps will dequeue as many tokens as there are workers before joining/quitting.
# This ensures parameter servers won't quit, if still required by at least one worker and
# also won't wait forever (like with a standard `server.join()`).
global done_queues
done_queues = []
for i, ps in enumerate(FLAGS.ps_hosts):
# Queues are hosted by their respective owners
with tf.device('/job:ps/task:%d' % i):
done_queues.append(tf.FIFOQueue(1, tf.int32, shared_name=('queue%i' % i)))
# Placeholder to pass in the worker's index as token
global token_placeholder
token_placeholder = tf.placeholder(tf.int32)
# Enqueue operations for each parameter server
global done_enqueues
done_enqueues = [queue.enqueue(token_placeholder) for queue in done_queues]
# Dequeue operations for each parameter server
global done_dequeues
done_dequeues = [queue.dequeue() for queue in done_queues]
if len(FLAGS.one_shot_infer) > 0:
FLAGS.train = False
FLAGS.test = False
FLAGS.export_dir = ''
if not os.path.exists(FLAGS.one_shot_infer):
log_error('Path specified in --one_shot_infer is not a valid file.')
exit(1)
if not os.path.exists(os.path.abspath(FLAGS.decoder_library_path)):
print('ERROR: The decoder library file does not exist. Make sure you have ' \
'downloaded or built the native client binaries and pass the ' \
'appropriate path to the binaries in the --decoder_library_path parameter.')
global custom_op_module
custom_op_module = tf.load_op_library(FLAGS.decoder_library_path)
# Logging functions
# =================
def prefix_print(prefix, message):
print(prefix + ('\n' + prefix).join(message.split('\n')))
def log_debug(message):
if FLAGS.log_level == 0:
prefix_print('D ', message)
def log_traffic(message):
if FLAGS.log_traffic:
log_debug(message)
def log_info(message):
if FLAGS.log_level <= 1:
prefix_print('I ', message)
def log_warn(message):
if FLAGS.log_level <= 2:
prefix_print('W ', message)
def log_error(message):
if FLAGS.log_level <= 3:
prefix_print('E ', message)
# Graph Creation
# ==============
def variable_on_worker_level(name, shape, initializer):
r'''
Next we concern ourselves with graph creation.
However, before we do so we must introduce a utility function ``variable_on_worker_level()``
used to create a variable in CPU memory.
'''
# Use the /cpu:0 device on worker_device for scoped operations
if len(FLAGS.ps_hosts) == 0:
device = worker_device
else:
device = tf.train.replica_device_setter(worker_device=worker_device, cluster=cluster)
with tf.device(device):
# Create or get apropos variable
var = tf.get_variable(name=name, shape=shape, initializer=initializer)
return var
def conv_output_length(input_length, filter_size, padding, stride,
dilation=1):
''' Compute the length of the output sequence after 1D convolution along
time.
Params:
input_length (int): Length of the input sequence.
filter_size (int): Width of the convolution kernel.
padding (str): Only support `SAME` or `VALID`.
stride (int): Stride size used in 1D convolution.
dilation (int)
'''
if input_length is None:
return None
assert padding in {'SAME', 'VALID'}
dilated_filter_size = filter_size + (filter_size - 1) * (dilation - 1)
if padding == 'SAME':
output_length = input_length
elif padding == 'VALID':
output_length = input_length - dilated_filter_size + 1
return (output_length + stride - 1) // stride
def decode_with_lm(inputs, sequence_length, beam_width=100,
top_paths=1, merge_repeated=True):
decoded_ixs, decoded_vals, decoded_shapes, log_probabilities = (
custom_op_module.ctc_beam_search_decoder_with_lm(
inputs, sequence_length, beam_width=beam_width,
model_path=FLAGS.lm_binary_path, trie_path=FLAGS.lm_trie_path, alphabet_path=FLAGS.alphabet_config_path,
lm_weight=FLAGS.lm_weight, word_count_weight=FLAGS.word_count_weight, valid_word_count_weight=FLAGS.valid_word_count_weight,
top_paths=top_paths, merge_repeated=merge_repeated))
return (
[tf.SparseTensor(ix, val, shape) for (ix, val, shape)
in zip(decoded_ixs, decoded_vals, decoded_shapes)],
log_probabilities)
def BiRNN(batch_x, seq_length, dropout, is_training, reuse):
# One layer of 1D convolution with SAME padding
with tf.variable_scope('conv1d') as scope:
layer_1 = tf.contrib.layers.convolution2d(
inputs=batch_x,
num_outputs=n_hidden,
kernel_size=[FLAGS.kernel_size],
stride=FLAGS.stride,
padding='SAME',
normalizer_fn=tf.contrib.layers.batch_norm,
normalizer_params={'is_training': is_training},
scope=scope,
reuse=reuse)
output_lengths = conv_output_length(seq_length, FLAGS.kernel_size, 'SAME', FLAGS.stride)
# Store individual statistics for a max of 10 seconds worth of time steps
# 10 seconds * (1/0.01) time steps per second = 1000 time steps
max_bn_steps = 1000
# Three layers of GRU cells with 1024 nodes each
cell = BNGRUCell(n_hidden, is_training, max_bn_steps=max_bn_steps, decay=FLAGS.decay)
multi_cell = tf.contrib.rnn.MultiRNNCell([cell] * FLAGS.recurrent_layers)
rnn_outputs, _ = tf.nn.dynamic_rnn(cell=multi_cell,
inputs=layer_1,
sequence_length=output_lengths,
dtype=tf.float32)
# A final fully connected layer with linear activation
with tf.variable_scope('fc') as scope:
network_output = tf.contrib.layers.fully_connected(
inputs=rnn_outputs,
num_outputs=n_character,
activation_fn=None,
scope=scope,
reuse=reuse)
# Transpose to time major
network_output = tf.transpose(network_output, [1, 0, 2])
# Output shape: [n_steps, batch_size, n_output]
return network_output, tf.cast(output_lengths, tf.int32)
# Accuracy and Loss
# =================
# In accord with 'Deep Speech: Scaling up end-to-end speech recognition'
# (http://arxiv.org/abs/1412.5567),
# the loss function used by our network should be the CTC loss function
# (http://www.cs.toronto.edu/~graves/preprint.pdf).
# Conveniently, this loss function is implemented in TensorFlow.
# Thus, we can simply make use of this implementation to define our loss.
def calculate_mean_edit_distance_and_loss(model_feeder, tower, dropout, is_training, reuse):
r'''
This routine beam search decodes a mini-batch and calculates the loss and mean edit distance.
Next to total and average loss it returns the mean edit distance,
the decoded result and the batch's original Y.
'''
# Obtain the next batch of data
batch_x, batch_seq_len, batch_y = model_feeder.next_batch(tower)
# Calculate the logits of the batch using BiRNN
logits, out_lengths = BiRNN(batch_x, tf.to_int64(batch_seq_len), dropout, is_training, reuse)
# Compute the CTC loss using either TensorFlow's `ctc_loss` or Baidu's `warp_ctc_loss`.
if FLAGS.use_warpctc:
total_loss = tf.contrib.warpctc.warp_ctc_loss(labels=batch_y, inputs=logits, sequence_length=out_lengths)
else:
total_loss = tf.nn.ctc_loss(labels=batch_y, inputs=logits, sequence_length=out_lengths)
# Calculate the average loss across the batch
avg_loss = tf.reduce_mean(total_loss)
# Beam search decode the batch
decoded, _ = decode_with_lm(logits, out_lengths, merge_repeated=False, beam_width=FLAGS.beam_width)
# Compute the edit (Levenshtein) distance
distance = tf.edit_distance(tf.cast(decoded[0], tf.int32), batch_y)
# Compute the mean edit distance
mean_edit_distance = tf.reduce_mean(distance)
# Finally we return the
# - calculated total and
# - average losses,
# - the Levenshtein distance,
# - the recognition mean edit distance,
# - the decoded batch and
# - the original batch_y (which contains the verified transcriptions).
return total_loss, avg_loss, distance, mean_edit_distance, decoded, batch_y
# Adam Optimization
# =================
# In contrast to 'Deep Speech: Scaling up end-to-end speech recognition'
# (http://arxiv.org/abs/1412.5567),
# in which 'Nesterov's Accelerated Gradient Descent'
# (www.cs.toronto.edu/~fritz/absps/momentum.pdf) was used,
# we will use the Adam method for optimization (http://arxiv.org/abs/1412.6980),
# because, generally, it requires less fine-tuning.
def create_optimizer():
optimizer = tf.train.AdamOptimizer(learning_rate=FLAGS.learning_rate,
beta1=FLAGS.beta1,
beta2=FLAGS.beta2,
epsilon=FLAGS.epsilon)
return optimizer
# Towers
# ======
# In order to properly make use of multiple GPU's, one must introduce new abstractions,
# not present when using a single GPU, that facilitate the multi-GPU use case.
# In particular, one must introduce a means to isolate the inference and gradient
# calculations on the various GPU's.
# The abstraction we intoduce for this purpose is called a 'tower'.
# A tower is specified by two properties:
# * **Scope** - A scope, as provided by `tf.name_scope()`,
# is a means to isolate the operations within a tower.
# For example, all operations within 'tower 0' could have their name prefixed with `tower_0/`.
# * **Device** - A hardware device, as provided by `tf.device()`,
# on which all operations within the tower execute.
# For example, all operations of 'tower 0' could execute on the first GPU `tf.device('/gpu:0')`.
def get_tower_results(model_feeder, optimizer, is_training):
r'''
With this preliminary step out of the way, we can for each GPU introduce a
tower for which's batch we calculate
* The CTC decodings ``decoded``,
* The (total) loss against the outcome (Y) ``total_loss``,
* The loss averaged over the whole batch ``avg_loss``,
* The optimization gradient (computed based on the averaged loss),
* The Levenshtein distances between the decodings and their transcriptions ``distance``,
* The mean edit distance of the outcome averaged over the whole batch ``mean_edit_distance``
and retain the original ``labels`` (Y).
``decoded``, ``labels``, the optimization gradient, ``distance``, ``mean_edit_distance``,
``total_loss`` and ``avg_loss`` are collected into the corresponding arrays
``tower_decodings``, ``tower_labels``, ``tower_gradients``, ``tower_distances``,
``tower_mean_edit_distances``, ``tower_total_losses``, ``tower_avg_losses`` (dimension 0 being the tower).
Finally this new method ``get_tower_results()`` will return those tower arrays.
In case of ``tower_mean_edit_distances`` and ``tower_avg_losses``, it will return the
averaged values instead of the arrays.
'''
# Tower labels to return
tower_labels = []
# Tower decodings to return
tower_decodings = []
# Tower distances to return
tower_distances = []
# Tower total batch losses to return
tower_total_losses = []
# Tower gradients to return
tower_gradients = []
# To calculate the mean of the mean edit distances
tower_mean_edit_distances = []
# To calculate the mean of the losses
tower_avg_losses = []
with tf.variable_scope(tf.get_variable_scope()):
# Loop over available_devices
for i in range(len(available_devices)):
# Execute operations of tower i on device i
if len(FLAGS.ps_hosts) == 0:
device = available_devices[i]
else:
device = tf.train.replica_device_setter(worker_device=available_devices[i], cluster=cluster)
with tf.device(device):
# Create a scope for all operations of tower i
with tf.name_scope('tower_%d' % i) as scope:
# Calculate the avg_loss and mean_edit_distance and retrieve the decoded
# batch along with the original batch's labels (Y) of this tower
total_loss, avg_loss, distance, mean_edit_distance, decoded, labels = \
calculate_mean_edit_distance_and_loss(model_feeder, i, no_dropout if optimizer is None else dropout_rates, is_training, i > 0)
# Allow for variables to be re-used by the next tower
tf.get_variable_scope().reuse_variables()
# Retain tower's labels (Y)
tower_labels.append(labels)
# Retain tower's decoded batch
tower_decodings.append(decoded)
# Retain tower's distances
tower_distances.append(distance)
# Retain tower's total losses
tower_total_losses.append(total_loss)
# Compute gradients for model parameters using tower's mini-batch
gradients = optimizer.compute_gradients(avg_loss)
# Retain tower's gradients
tower_gradients.append(gradients)
# Retain tower's mean edit distance
tower_mean_edit_distances.append(mean_edit_distance)
# Retain tower's avg losses
tower_avg_losses.append(avg_loss)
# Return the results tuple, the gradients, and the means of mean edit distances and losses
return (tower_labels, tower_decodings, tower_distances, tower_total_losses), \
tower_gradients, \
tf.reduce_mean(tower_mean_edit_distances, 0), \
tf.reduce_mean(tower_avg_losses, 0)
def average_gradients(tower_gradients):
r'''
A routine for computing each variable's average of the gradients obtained from the GPUs.
Note also that this code acts as a synchronization point as it requires all
GPUs to be finished with their mini-batch before it can run to completion.
'''
# List of average gradients to return to the caller
average_grads = []
# Run this on cpu_device to conserve GPU memory
with tf.device(cpu_device):
# Loop over gradient/variable pairs from all towers
for grad_and_vars in zip(*tower_gradients):
# Introduce grads to store the gradients for the current variable
grads = []
# Loop over the gradients for the current variable
for g, _ in grad_and_vars:
# Add 0 dimension to the gradients to represent the tower.
expanded_g = tf.expand_dims(g, 0)
# Append on a 'tower' dimension which we will average over below.
grads.append(expanded_g)
# Average over the 'tower' dimension
grad = tf.concat(grads, 0)
grad = tf.reduce_mean(grad, 0)
# Create a gradient/variable tuple for the current variable with its average gradient
grad_and_var = (grad, grad_and_vars[0][1])
# Add the current tuple to average_grads
average_grads.append(grad_and_var)
# Return result to caller
return average_grads
# Logging
# =======
def log_variable(variable, gradient=None):
r'''
We introduce a function for logging a tensor variable's current state.
It logs scalar values for the mean, standard deviation, minimum and maximum.
Furthermore it logs a histogram of its state and (if given) of an optimization gradient.
'''
name = variable.name
mean = tf.reduce_mean(variable)
tf.summary.scalar(name='%s/mean' % name, tensor=mean)
tf.summary.scalar(name='%s/sttdev' % name, tensor=tf.sqrt(tf.reduce_mean(tf.square(variable - mean))))
tf.summary.scalar(name='%s/max' % name, tensor=tf.reduce_max(variable))
tf.summary.scalar(name='%s/min' % name, tensor=tf.reduce_min(variable))
tf.summary.histogram(name=name, values=variable)
if gradient is not None:
if isinstance(gradient, tf.IndexedSlices):
grad_values = gradient.values
else:
grad_values = gradient
if grad_values is not None:
tf.summary.histogram(name='%s/gradients' % name, values=grad_values)
def log_grads_and_vars(grads_and_vars):
r'''
Let's also introduce a helper function for logging collections of gradient/variable tuples.
'''
for gradient, variable in grads_and_vars:
log_variable(variable, gradient=gradient)
def get_git_revision_hash():
return subprocess.check_output(['git', 'rev-parse', 'HEAD']).strip()
def get_git_branch():
return subprocess.check_output(['git', 'rev-parse', '--abbrev-ref', 'HEAD']).strip()
# Helpers
# =======
def calculate_report(results_tuple):
r'''
This routine will calculate a WER report.
It'll compute the `mean` WER and create ``Sample`` objects of the ``report_count`` top lowest
loss items from the provided WER results tuple (only items with WER!=0 and ordered by their WER).
'''
samples = []
items = list(zip(*results_tuple))
total_levenshtein = 0.0
total_label_length = 0.0
for label, decoding, distance, loss in items:
sample_wer = wer(label, decoding)
sample = Sample(label, decoding, loss, distance, sample_wer)
samples.append(sample)
total_levenshtein += levenshtein(label.split(), decoding.split())
total_label_length += float(len(label.split()))
# Getting the WER from the accumulated levenshteins and lengths
samples_wer = total_levenshtein / total_label_length
# Filter out all items with WER=0
samples = [s for s in samples if s.wer > 0]
# Order the remaining items by their loss (lowest loss on top)
samples.sort(key=lambda s: s.loss)
# Take only the first report_count items
samples = samples[:FLAGS.report_count]
# Order this top FLAGS.report_count items by their WER (lowest WER on top)
samples.sort(key=lambda s: s.wer)
return samples_wer, samples
def collect_results(results_tuple, returns):
r'''
This routine will help collecting partial results for the WER reports.
The ``results_tuple`` is composed of an array of the original labels,
an array of the corresponding decodings, an array of the corrsponding
distances and an array of the corresponding losses. ``returns`` is built up
in a similar way, containing just the unprocessed results of one
``session.run`` call (effectively of one batch).
Labels and decodings are converted to text before splicing them into their
corresponding results_tuple lists. In the case of decodings,
for now we just pick the first available path.
'''
# Each of the arrays within results_tuple will get extended by a batch of each available device
for i in range(len(available_devices)):
# Collect the labels
results_tuple[0].extend(sparse_tensor_value_to_texts(returns[0][i], alphabet))
# Collect the decodings - at the moment we default to the first one
results_tuple[1].extend(sparse_tensor_value_to_texts(returns[1][i][0], alphabet))
# Collect the distances
results_tuple[2].extend(returns[2][i])
# Collect the losses
results_tuple[3].extend(returns[3][i])
# For reporting we also need a standard way to do time measurements.
def stopwatch(start_duration=0):
r'''
This function will toggle a stopwatch.
The first call starts it, second call stops it, third call continues it etc.
So if you want to measure the accumulated time spent in a certain area of the code,
you can surround that code by stopwatch-calls like this:
.. code:: python
fun_time = 0 # initializes a stopwatch
[...]
for i in range(10):
[...]
# Starts/continues the stopwatch - fun_time is now a point in time (again)
fun_time = stopwatch(fun_time)
fun()
# Pauses the stopwatch - fun_time is now a duration
fun_time = stopwatch(fun_time)
[...]
# The following line only makes sense after an even call of :code:`fun_time = stopwatch(fun_time)`.
print 'Time spent in fun():', format_duration(fun_time)
'''
if start_duration == 0:
return datetime.datetime.utcnow()
else:
return datetime.datetime.utcnow() - start_duration
def format_duration(duration):
'''Formats the result of an even stopwatch call as hours:minutes:seconds'''
duration = duration if isinstance(duration, int) else duration.seconds
m, s = divmod(duration, 60)
h, m = divmod(m, 60)
return '%d:%02d:%02d' % (h, m, s)
# Execution
# =========
# String constants for different services of the web handler
PREFIX_NEXT_INDEX = '/next_index_'
PREFIX_GET_JOB = '/get_job_'
# Global ID counter for all objects requiring an ID
id_counter = 0
def new_id():
'''Returns a new ID that is unique on process level. Not thread-safe.
Returns:
int. The new ID
'''
global id_counter
id_counter += 1
return id_counter
class Sample(object):
def __init__(self, src, res, loss, mean_edit_distance, sample_wer):
'''Represents one item of a WER report.
Args:
src (str): source text
res (str): resulting text
loss (float): computed loss of this item
mean_edit_distance (float): computed mean edit distance of this item
'''
self.src = src
self.res = res
self.loss = loss
self.mean_edit_distance = mean_edit_distance
self.wer = sample_wer
def __str__(self):
return 'WER: %f, loss: %f, mean edit distance: %f\n - src: "%s"\n - res: "%s"' % (self.wer, self.loss, self.mean_edit_distance, self.src, self.res)
class WorkerJob(object):
def __init__(self, epoch_id, index, set_name, steps, report):
'''Represents a job that should be executed by a worker.
Args:
epoch_id (int): the ID of the 'parent' epoch
index (int): the epoch index of the 'parent' epoch
set_name (str): the name of the data-set - one of 'train', 'dev', 'test'
steps (int): the number of `session.run` calls
report (bool): if this job should produce a WER report
'''
self.id = new_id()
self.epoch_id = epoch_id
self.index = index
self.worker = -1
self.set_name = set_name
self.steps = steps
self.report = report
self.loss = -1
self.mean_edit_distance = -1
self.wer = -1
self.samples = []
def __str__(self):
return 'Job (ID: %d, worker: %d, epoch: %d, set_name: %s)' % (self.id, self.worker, self.index, self.set_name)
class Epoch(object):
'''Represents an epoch that should be executed by the Training Coordinator.
Creates `num_jobs` `WorkerJob` instances in state 'open'.
Args:
index (int): the epoch index of the 'parent' epoch
num_jobs (int): the number of jobs in this epoch
Kwargs:
set_name (str): the name of the data-set - one of 'train', 'dev', 'test'
report (bool): if this job should produce a WER report
'''
def __init__(self, index, num_jobs, set_name='train', report=False):
self.id = new_id()
self.index = index
self.num_jobs = num_jobs
self.set_name = set_name
self.report = report
self.wer = -1
self.loss = -1
self.mean_edit_distance = -1
self.jobs_open = []
self.jobs_running = []
self.jobs_done = []
self.samples = []
for i in range(self.num_jobs):
self.jobs_open.append(WorkerJob(self.id, self.index, self.set_name, FLAGS.iters_per_worker, self.report))
def name(self):
'''Gets a printable name for this epoch.
Returns:
str. printable name for this epoch
'''
if self.index >= 0:
ename = ' of Epoch %d' % self.index
else:
ename = ''
if self.set_name == 'train':
return 'Training%s' % ename
elif self.set_name == 'dev':
return 'Validation%s' % ename
else:
return 'Test%s' % ename
def get_job(self, worker):
'''Gets the next open job from this epoch. The job will be marked as 'running'.
Args:
worker (int): index of the worker that takes the job
Returns:
WorkerJob. job that has been marked as running for this worker
'''
if len(self.jobs_open) > 0:
job = self.jobs_open.pop(0)
self.jobs_running.append(job)
job.worker = worker
return job
else:
return None
def finish_job(self, job):
'''Finishes a running job. Removes it from the running jobs list and adds it to the done jobs list.
Args:
job (WorkerJob): the job to put into state 'done'
'''
index = next((i for i in range(len(self.jobs_running)) if self.jobs_running[i].id == job.id), -1)
if index >= 0:
self.jobs_running.pop(index)
self.jobs_done.append(job)
log_traffic('%s - Moved %s from running to done.' % (self.name(), job))
else:
log_warn('%s - There is no job with ID %d registered as running.' % (self.name(), job.id))
def done(self):
'''Checks, if all jobs of the epoch are in state 'done'.
It also lazy-prepares a WER report from the result data of all jobs.
Returns:
bool. if all jobs of the epoch are 'done'
'''
if len(self.jobs_open) == 0 and len(self.jobs_running) == 0:
num_jobs = len(self.jobs_done)
if num_jobs > 0:
jobs = self.jobs_done
self.jobs_done = []
if not self.num_jobs == num_jobs:
log_warn('%s - Number of steps not equal to number of jobs done.' % (self.name()))
agg_loss = 0.0
agg_wer = 0.0
agg_mean_edit_distance = 0.0
for i in range(num_jobs):
job = jobs.pop(0)
agg_loss += job.loss
if self.report:
agg_wer += job.wer
agg_mean_edit_distance += job.mean_edit_distance
self.samples.extend(job.samples)
self.loss = agg_loss / num_jobs
# if the job was for validation dataset then append it to the COORD's _loss for early stop verification
if (FLAGS.early_stop is True) and (self.set_name == 'dev'):
COORD._dev_losses.append(self.loss)
if self.report:
self.wer = agg_wer / num_jobs