Merge pull request #2763 from reuben/transfer-learning-rebase

Transfer learning support

DeepSpeech.py

@@ -6,7 +6,8 @@ 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 0 < LOG_LEVEL_INDEX < len(sys.argv) else '3'
+DESIRED_LOG_LEVEL = sys.argv[LOG_LEVEL_INDEX] if 0 < LOG_LEVEL_INDEX < len(sys.argv) else '3'
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = DESIRED_LOG_LEVEL
 
 import absl.app
 import json
@@ -17,18 +18,25 @@ import tensorflow as tf
 import tensorflow.compat.v1 as tfv1
 import time
 
+tfv1.logging.set_verbosity({
+    '0': tfv1.logging.DEBUG,
+    '1': tfv1.logging.INFO,
+    '2': tfv1.logging.WARN,
+    '3': tfv1.logging.ERROR
+}.get(DESIRED_LOG_LEVEL))
+
 from datetime import datetime
 from ds_ctcdecoder import ctc_beam_search_decoder, Scorer
 from evaluate import evaluate
 from six.moves import zip, range
-from tensorflow.python.tools import freeze_graph, strip_unused_lib
-from tensorflow.python.framework import errors_impl
 from util.config import Config, initialize_globals
+from util.checkpoints import load_or_init_graph
 from util.feeding import create_dataset, samples_to_mfccs, audiofile_to_features
 from util.flags import create_flags, FLAGS
+from util.helpers import check_ctcdecoder_version
 from util.logging import log_info, log_error, log_debug, log_progress, create_progressbar
-from util.helpers import check_ctcdecoder_version; check_ctcdecoder_version()
 
+check_ctcdecoder_version()
 
 # Graph Creation
 # ==============
@@ -222,7 +230,7 @@ def calculate_mean_edit_distance_and_loss(iterator, dropout, reuse):
     # Obtain the next batch of data
     batch_filenames, (batch_x, batch_seq_len), batch_y = iterator.get_next()
 
-    if FLAGS.use_cudnn_rnn:
+    if FLAGS.train_cudnn:
         rnn_impl = rnn_impl_cudnn_rnn
     else:
         rnn_impl = rnn_impl_lstmblockfusedcell
@@ -397,30 +405,6 @@ def log_grads_and_vars(grads_and_vars):
         log_variable(variable, gradient=gradient)
 
 
-def try_loading(session, saver, checkpoint_filename, caption, load_step=True, log_success=True):
-    try:
-        checkpoint = tf.train.get_checkpoint_state(FLAGS.checkpoint_dir, checkpoint_filename)
-        if not checkpoint:
-            return False
-        checkpoint_path = checkpoint.model_checkpoint_path
-        saver.restore(session, checkpoint_path)
-        if load_step:
-            restored_step = session.run(tfv1.train.get_global_step())
-            if log_success:
-                log_info('Restored variables from %s checkpoint at %s, step %d' %
-                         (caption, checkpoint_path, restored_step))
-        elif log_success:
-            log_info('Restored variables from %s checkpoint at %s' % (caption, checkpoint_path))
-        return True
-    except tf.errors.InvalidArgumentError as e:
-        log_error(str(e))
-        log_error('The checkpoint in {0} does not match the shapes of the model.'
-                  ' Did you change alphabet.txt or the --n_hidden parameter'
-                  ' between train runs using the same checkpoint dir? Try moving'
-                  ' or removing the contents of {0}.'.format(checkpoint_path))
-        sys.exit(1)
-
-
 def train():
     do_cache_dataset = True
 
@@ -494,76 +478,29 @@ def train():
 
     # Checkpointing
     checkpoint_saver = tfv1.train.Saver(max_to_keep=FLAGS.max_to_keep)
-    checkpoint_path = os.path.join(FLAGS.checkpoint_dir, 'train')
+    checkpoint_path = os.path.join(FLAGS.save_checkpoint_dir, 'train')
 
     best_dev_saver = tfv1.train.Saver(max_to_keep=1)
-    best_dev_path = os.path.join(FLAGS.checkpoint_dir, 'best_dev')
+    best_dev_path = os.path.join(FLAGS.save_checkpoint_dir, 'best_dev')
 
     # Save flags next to checkpoints
-    os.makedirs(FLAGS.checkpoint_dir, exist_ok=True)
+    os.makedirs(FLAGS.save_checkpoint_dir, exist_ok=True)
-
+    flags_file = os.path.join(FLAGS.save_checkpoint_dir, 'flags.txt')
-    flags_file = os.path.join(FLAGS.checkpoint_dir, 'flags.txt')
     with open(flags_file, 'w') as fout:
         fout.write(FLAGS.flags_into_string())
 
-    initializer = tfv1.global_variables_initializer()
-
     with tfv1.Session(config=Config.session_config) as session:
         log_debug('Session opened.')
 
-        # Loading or initializing
+        # Prevent further graph changes
-        loaded = False
-
-        # Initialize training from a CuDNN RNN checkpoint
-        if FLAGS.cudnn_checkpoint:
-            if FLAGS.use_cudnn_rnn:
-                log_error('Trying to use --cudnn_checkpoint but --use_cudnn_rnn '
-                          'was specified. The --cudnn_checkpoint flag is only '
-                          'needed when converting a CuDNN RNN checkpoint to '
-                          'a CPU-capable graph. If your system is capable of '
-                          'using CuDNN RNN, you can just specify the CuDNN RNN '
-                          'checkpoint normally with --checkpoint_dir.')
-                sys.exit(1)
-
-            log_info('Converting CuDNN RNN checkpoint from {}'.format(FLAGS.cudnn_checkpoint))
-            ckpt = tfv1.train.load_checkpoint(FLAGS.cudnn_checkpoint)
-            missing_variables = []
-
-            # Load compatible variables from checkpoint
-            for v in tfv1.global_variables():
-                try:
-                    v.load(ckpt.get_tensor(v.op.name), session=session)
-                except tf.errors.NotFoundError:
-                    missing_variables.append(v)
-
-            # Check that the only missing variables are the Adam moment tensors
-            if any('Adam' not in v.op.name for v in missing_variables):
-                log_error('Tried to load a CuDNN RNN checkpoint but there were '
-                          'more missing variables than just the Adam moment '
-                          'tensors.')
-                sys.exit(1)
-
-            # Initialize Adam moment tensors from scratch to allow use of CuDNN
-            # RNN checkpoints.
-            log_info('Initializing missing Adam moment tensors.')
-            init_op = tfv1.variables_initializer(missing_variables)
-            session.run(init_op)
-            loaded = True
-
         tfv1.get_default_graph().finalize()
 
-        if not loaded and FLAGS.load in ['auto', 'last']:
+        # Load checkpoint or initialize variables
-            loaded = try_loading(session, checkpoint_saver, 'checkpoint', 'most recent')
+        if FLAGS.load == 'auto':
-        if not loaded and FLAGS.load in ['auto', 'best']:
+            method_order = ['best', 'last', 'init']
-            loaded = try_loading(session, best_dev_saver, 'best_dev_checkpoint', 'best validation')
-        if not loaded:
-            if FLAGS.load in ['auto', 'init']:
-                log_info('Initializing variables...')
-                session.run(initializer)
         else:
-                log_error('Unable to load %s model from specified checkpoint dir'
+            method_order = [FLAGS.load]
-                          ' - consider using load option "auto" or "init".' % FLAGS.load)
+        load_or_init_graph(session, method_order)
-                sys.exit(1)
 
         def run_set(set_name, epoch, init_op, dataset=None):
             is_train = set_name == 'train'
@@ -682,7 +619,7 @@ def train():
 
 
 def test():
-    samples = evaluate(FLAGS.test_files.split(','), create_model, try_loading)
+    samples = evaluate(FLAGS.test_files.split(','), create_model)
     if FLAGS.test_output_file:
         # Save decoded tuples as JSON, converting NumPy floats to Python floats
         json.dump(samples, open(FLAGS.test_output_file, 'w'), default=float)
@@ -803,49 +740,40 @@ def export():
     if FLAGS.export_language:
         outputs['metadata_language'] = tf.constant([FLAGS.export_language.encode('utf-8')], name='metadata_language')
 
+    # Prevent further graph changes
+    tfv1.get_default_graph().finalize()
+
     output_names_tensors = [tensor.op.name for tensor in outputs.values() if isinstance(tensor, Tensor)]
     output_names_ops = [op.name for op in outputs.values() if isinstance(op, Operation)]
-    output_names = ",".join(output_names_tensors + output_names_ops)
+    output_names = output_names_tensors + output_names_ops
 
-    # Create a saver using variables from the above newly created graph
+    with tf.Session() as session:
-    saver = tfv1.train.Saver()
+        # Restore variables from checkpoint
-
+        if FLAGS.load == 'auto':
-    # Restore variables from training checkpoint
+            method_order = ['best', 'last']
-    checkpoint = tf.train.get_checkpoint_state(FLAGS.checkpoint_dir)
+        else:
-    checkpoint_path = checkpoint.model_checkpoint_path
+            method_order = [FLAGS.load]
+        load_or_init_graph(session, method_order)
 
         output_filename = FLAGS.export_name + '.pb'
         if FLAGS.remove_export:
             if os.path.isdir(FLAGS.export_dir):
                 log_info('Removing old export')
                 shutil.rmtree(FLAGS.export_dir)
-    try:
+
         output_graph_path = os.path.join(FLAGS.export_dir, output_filename)
 
         if not os.path.isdir(FLAGS.export_dir):
             os.makedirs(FLAGS.export_dir)
 
-        def do_graph_freeze(output_file=None, output_node_names=None, variables_blacklist=''):
+        frozen_graph = tfv1.graph_util.convert_variables_to_constants(
-            frozen = freeze_graph.freeze_graph_with_def_protos(
+            sess=session,
             input_graph_def=tfv1.get_default_graph().as_graph_def(),
-                input_saver_def=saver.as_saver_def(),
+            output_node_names=output_names)
-                input_checkpoint=checkpoint_path,
-                output_node_names=output_node_names,
-                restore_op_name=None,
-                filename_tensor_name=None,
-                output_graph=output_file,
-                clear_devices=False,
-                variable_names_blacklist=variables_blacklist,
-                initializer_nodes='')
 
-            input_node_names = []
+        frozen_graph = tfv1.graph_util.extract_sub_graph(
-            return strip_unused_lib.strip_unused(
+            graph_def=frozen_graph,
-                input_graph_def=frozen,
+            dest_nodes=output_names)
-                input_node_names=input_node_names,
-                output_node_names=output_node_names.split(','),
-                placeholder_type_enum=tf.float32.as_datatype_enum)
-
-        frozen_graph = do_graph_freeze(output_node_names=output_names)
 
         if not FLAGS.export_tflite:
             with open(output_graph_path, 'wb') as fout:
@@ -854,7 +782,7 @@ def export():
             output_tflite_path = os.path.join(FLAGS.export_dir, output_filename.replace('.pb', '.tflite'))
 
             converter = tf.lite.TFLiteConverter(frozen_graph, input_tensors=inputs.values(), output_tensors=outputs.values())
-            converter.optimizations = [ tf.lite.Optimize.DEFAULT ]
+            converter.optimizations = [tf.lite.Optimize.DEFAULT]
             # AudioSpectrogram and Mfcc ops are custom but have built-in kernels in TFLite
             converter.allow_custom_ops = True
             tflite_model = converter.convert()
@@ -862,11 +790,7 @@ def export():
             with open(output_tflite_path, 'wb') as fout:
                 fout.write(tflite_model)
 
-            log_info('Exported model for TF Lite engine as {}'.format(os.path.basename(output_tflite_path)))
-
         log_info('Models exported at %s' % (FLAGS.export_dir))
-    except RuntimeError as e:
-        log_error(str(e))
 
 def package_zip():
     # --export_dir path/to/export/LANG_CODE/ => path/to/export/LANG_CODE.zip
@@ -887,18 +811,12 @@ def do_single_file_inference(input_file_path):
     with tfv1.Session(config=Config.session_config) as session:
         inputs, outputs, _ = create_inference_graph(batch_size=1, n_steps=-1)
 
-        # Create a saver using variables from the above newly created graph
-        saver = tfv1.train.Saver()
-
         # Restore variables from training checkpoint
-        loaded = False
+        if FLAGS.load == 'auto':
-        if not loaded and FLAGS.load in ['auto', 'last']:
+            method_order = ['best', 'last']
-            loaded = try_loading(session, saver, 'checkpoint', 'most recent', load_step=False)
+        else:
-        if not loaded and FLAGS.load in ['auto', 'best']:
+            method_order = [FLAGS.load]
-            loaded = try_loading(session, saver, 'best_dev_checkpoint', 'best validation', load_step=False)
+        load_or_init_graph(session, method_order)
-        if not loaded:
-            print('Could not load checkpoint from {}'.format(FLAGS.checkpoint_dir))
-            sys.exit(1)
 
         features, features_len = audiofile_to_features(input_file_path)
         previous_state_c = np.zeros([1, Config.n_cell_dim])

bin/run-tc-ldc93s1_checkpoint.sh

@@ -23,7 +23,7 @@ python -u DeepSpeech.py --noshow_progressbar --noearly_stop \
   --learning_rate 0.001 --dropout_rate 0.05 \
   --scorer_path 'data/smoke_test/pruned_lm.scorer' | tee /tmp/resume.log
 
-if ! grep "Restored variables from most recent checkpoint" /tmp/resume.log; then
+if ! grep "Loading best validating checkpoint from" /tmp/resume.log; then
   echo "Did not resume training from checkpoint"
   exit 1
 else

bin/run-tc-transfer.sh

@@ -0,0 +1,126 @@
+#!/bin/sh
+# This bash script is for running minimum working examples
+# of transfer learning for continuous integration tests
+# to be run on Taskcluster.
+set -xe
+
+ru_dir="./data/smoke_test/russian_sample_data"
+ru_csv="${ru_dir}/ru.csv"
+
+ldc93s1_dir="./data/smoke_test"
+ldc93s1_csv="${ldc93s1_dir}/ldc93s1.csv"
+
+if [ ! -f "${ldc93s1_dir}/ldc93s1.csv" ]; then
+    echo "Downloading and preprocessing LDC93S1 example data, saving in ${ldc93s1_dir}."
+    python -u bin/import_ldc93s1.py ${ldc93s1_dir}
+fi;
+
+# Force only one visible device because we have a single-sample dataset
+# and when trying to run on multiple devices (like GPUs), this will break
+export CUDA_VISIBLE_DEVICES=0
+
+# Force UTF-8 output
+export PYTHONIOENCODING=utf-8
+
+echo "##### Train ENGLISH model and transfer to RUSSIAN #####"
+echo "##### while iterating over loading logic #####"
+
+for LOAD in 'init' 'last' 'auto'; do
+    echo "########################################################"
+    echo "#### Train ENGLISH model with just --checkpoint_dir ####"
+    echo "########################################################"
+    python -u DeepSpeech.py --noshow_progressbar --noearly_stop \
+       --alphabet_config_path "./data/alphabet.txt" \
+       --load "$LOAD" \
+       --train_files  "${ldc93s1_csv}" --train_batch_size 1  \
+       --dev_files  "${ldc93s1_csv}" --dev_batch_size 1 \
+       --test_files  "${ldc93s1_csv}" --test_batch_size 1 \
+       --scorer_path '' \
+       --checkpoint_dir '/tmp/ckpt/transfer/eng' \
+       --n_hidden 100 \
+       --epochs 10
+
+    echo "##############################################################################"
+    echo "#### Train ENGLISH model with --save_checkpoint_dir --load_checkpoint_dir ####"
+    echo "##############################################################################"
+    python -u DeepSpeech.py --noshow_progressbar --noearly_stop \
+           --alphabet_config_path "./data/alphabet.txt" \
+           --load "$LOAD" \
+           --train_files  "${ldc93s1_csv}" --train_batch_size 1  \
+           --dev_files  "${ldc93s1_csv}" --dev_batch_size 1 \
+           --test_files  "${ldc93s1_csv}" --test_batch_size 1 \
+           --save_checkpoint_dir '/tmp/ckpt/transfer/eng' \
+           --load_checkpoint_dir '/tmp/ckpt/transfer/eng' \
+           --scorer_path '' \
+           --n_hidden 100 \
+           --epochs 10
+
+    echo "#################################################################################"
+    echo "#### Transfer Russian model with --save_checkpoint_dir --load_checkpoint_dir ####"
+    echo "#################################################################################"
+    python -u DeepSpeech.py --noshow_progressbar --noearly_stop \
+           --drop_source_layers 1 \
+           --alphabet_config_path "${ru_dir}/alphabet.ru" \
+           --load 'last' \
+           --train_files  "${ru_csv}" --train_batch_size 1  \
+           --dev_files  "${ru_csv}" --dev_batch_size 1 \
+           --test_files  "${ru_csv}" --test_batch_size 1 \
+           --save_checkpoint_dir '/tmp/ckpt/transfer/ru' \
+           --load_checkpoint_dir '/tmp/ckpt/transfer/eng' \
+           --scorer_path '' \
+           --n_hidden 100 \
+           --epochs 10
+done
+
+echo "#######################################################"
+echo "##### Train ENGLISH model and transfer to RUSSIAN #####"
+echo "##### while iterating over loading logic          #####"
+echo "#######################################################"
+
+for LOAD in 'init' 'last' 'auto'; do
+    echo "########################################################"
+    echo "#### Train ENGLISH model with just --checkpoint_dir ####"
+    echo "########################################################"
+    python -u DeepSpeech.py --noshow_progressbar --noearly_stop \
+       --alphabet_config_path "./data/alphabet.txt" \
+       --load "$LOAD" \
+       --train_files  "${ldc93s1_csv}" --train_batch_size 1  \
+       --dev_files  "${ldc93s1_csv}" --dev_batch_size 1 \
+       --test_files  "${ldc93s1_csv}" --test_batch_size 1 \
+       --checkpoint_dir '/tmp/ckpt/transfer/eng' \
+       --scorer_path '' \
+       --n_hidden 100 \
+       --epochs 10
+
+
+    echo "##############################################################################"
+    echo "#### Train ENGLISH model with --save_checkpoint_dir --load_checkpoint_dir ####"
+    echo "##############################################################################"
+    python -u DeepSpeech.py --noshow_progressbar --noearly_stop \
+           --alphabet_config_path "./data/alphabet.txt" \
+           --load "$LOAD" \
+           --train_files  "${ldc93s1_csv}" --train_batch_size 1  \
+           --dev_files  "${ldc93s1_csv}" --dev_batch_size 1 \
+           --test_files  "${ldc93s1_csv}" --test_batch_size 1 \
+           --save_checkpoint_dir '/tmp/ckpt/transfer/eng' \
+           --load_checkpoint_dir '/tmp/ckpt/transfer/eng' \
+           --scorer_path '' \
+           --n_hidden 100 \
+           --epochs 10
+
+    echo "####################################################################################"
+    echo "#### Transfer to RUSSIAN model with --save_checkpoint_dir --load_checkpoint_dir ####"
+    echo "####################################################################################"
+    python -u DeepSpeech.py --noshow_progressbar --noearly_stop \
+           --drop_source_layers 1 \
+           --alphabet_config_path "${ru_dir}/alphabet.ru" \
+           --load 'last' \
+           --train_files  "${ru_csv}" --train_batch_size 1  \
+           --dev_files  "${ru_csv}" --dev_batch_size 1 \
+           --test_files  "${ru_csv}" --test_batch_size 1 \
+           --save_checkpoint_dir '/tmp/ckpt/transfer/ru' \
+           --load_checkpoint_dir '/tmp/ckpt/transfer/eng' \
+           --scorer_path '' \
+           --n_hidden 100 \
+           --epochs 10
+done

data/smoke_test/russian_sample_data/alphabet.ru

@@ -0,0 +1,34 @@
+ 
+о
+е
+а
+и
+н
+т
+с
+л
+в
+р
+к
+м
+д
+п
+ы
+у
+б
+я
+ь
+г
+з
+ч
+й
+ж
+х
+ш
+ю
+ц
+э
+щ
+ф
+ё
+ъ

data/smoke_test/russian_sample_data/ru.csv

@@ -0,0 +1,2 @@
+wav_filename,wav_filesize,transcript
+ru.wav,0,бедняга ребят на его месте должен был быть я

evaluate.py

@@ -16,12 +16,14 @@ from ds_ctcdecoder import ctc_beam_search_decoder_batch, Scorer
 from six.moves import zip
 
 from util.config import Config, initialize_globals
+from util.checkpoints import load_or_init_graph
 from util.evaluate_tools import calculate_and_print_report
 from util.feeding import create_dataset
 from util.flags import create_flags, FLAGS
+from util.helpers import check_ctcdecoder_version
 from util.logging import create_progressbar, log_error, log_progress
-from util.helpers import check_ctcdecoder_version; check_ctcdecoder_version()
 
+check_ctcdecoder_version()
 
 def sparse_tensor_value_to_texts(value, alphabet):
     r"""
@@ -41,7 +43,7 @@ def sparse_tuple_to_texts(sp_tuple, alphabet):
     return [alphabet.decode(res) for res in results]
 
 
-def evaluate(test_csvs, create_model, try_loading):
+def evaluate(test_csvs, create_model):
     if FLAGS.scorer_path:
         scorer = Scorer(FLAGS.lm_alpha, FLAGS.lm_beta,
                         FLAGS.scorer_path, Config.alphabet)
@@ -79,19 +81,12 @@ def evaluate(test_csvs, create_model, try_loading):
     except NotImplementedError:
         num_processes = 1
 
-    # Create a saver using variables from the above newly created graph
-    saver = tfv1.train.Saver()
-
     with tfv1.Session(config=Config.session_config) as session:
-        # Restore variables from training checkpoint
+        if FLAGS.load == 'auto':
-        loaded = False
+            method_order = ['best', 'last']
-        if not loaded and FLAGS.load in ['auto', 'best']:
+        else:
-            loaded = try_loading(session, saver, 'best_dev_checkpoint', 'best validation')
+            method_order = [FLAGS.load]
-        if not loaded and FLAGS.load in ['auto', 'last']:
+        load_or_init_graph(session, method_order)
-            loaded = try_loading(session, saver, 'checkpoint', 'most recent')
-        if not loaded:
-            print('Could not load checkpoint from {}'.format(FLAGS.checkpoint_dir))
-            sys.exit(1)
 
         def run_test(init_op, dataset):
             wav_filenames = []
@@ -148,8 +143,8 @@ def main(_):
                   'the --test_files flag.')
         sys.exit(1)
 
-    from DeepSpeech import create_model, try_loading # pylint: disable=cyclic-import
+    from DeepSpeech import create_model # pylint: disable=cyclic-import,import-outside-toplevel
-    samples = evaluate(FLAGS.test_files.split(','), create_model, try_loading)
+    samples = evaluate(FLAGS.test_files.split(','), create_model)
 
     if FLAGS.test_output_file:
         # Save decoded tuples as JSON, converting NumPy floats to Python floats

taskcluster/tc-transfer-tests.sh

@@ -0,0 +1,65 @@
+#!/bin/bash
+
+set -xe
+
+source $(dirname "$0")/tc-tests-utils.sh
+
+pyver_full=$1
+
+if [ -z "${pyver_full}" ]; then
+    echo "No python version given, aborting."
+    exit 1
+fi;
+
+pyver=$(echo "${pyver_full}" | cut -d':' -f1)
+
+# 2.7.x => 27
+pyver_pkg=$(echo "${pyver}" | cut -d'.' -f1,2 | tr -d '.')
+
+py_unicode_type=$(echo "${pyver_full}" | cut -d':' -f2)
+if [ "${py_unicode_type}" = "m" ]; then
+  pyconf="ucs2"
+elif [ "${py_unicode_type}" = "mu" ]; then
+  pyconf="ucs4"
+fi;
+
+unset PYTHON_BIN_PATH
+unset PYTHONPATH
+export PYENV_ROOT="${HOME}/ds-train/.pyenv"
+export PATH="${PYENV_ROOT}/bin:${HOME}/bin:$PATH"
+
+mkdir -p ${PYENV_ROOT} || true
+mkdir -p ${TASKCLUSTER_ARTIFACTS} || true
+mkdir -p /tmp/train || true
+mkdir -p /tmp/train_tflite || true
+
+install_pyenv "${PYENV_ROOT}"
+install_pyenv_virtualenv "$(pyenv root)/plugins/pyenv-virtualenv"
+
+PYENV_NAME=deepspeech-train
+PYTHON_CONFIGURE_OPTS="--enable-unicode=${pyconf}" pyenv install ${pyver}
+pyenv virtualenv ${pyver} ${PYENV_NAME}
+source ${PYENV_ROOT}/versions/${pyver}/envs/${PYENV_NAME}/bin/activate
+
+set -o pipefail
+pip install --upgrade pip==19.3.1 setuptools==45.0.0 wheel==0.33.6 | cat
+pip install --upgrade -r ${HOME}/DeepSpeech/ds/requirements.txt | cat
+set +o pipefail
+
+pushd ${HOME}/DeepSpeech/ds/
+    verify_ctcdecoder_url
+popd
+
+platform=$(python -c 'import sys; import platform; plat = platform.system().lower(); arch = platform.machine().lower(); plat = "manylinux1" if plat == "linux" and arch == "x86_64" else plat; plat = "macosx_10_10" if plat == "darwin" else plat; sys.stdout.write("%s_%s" % (plat, platform.machine()));')
+whl_ds_version="$(python -c 'from pkg_resources import parse_version; print(parse_version("'${DS_VERSION}'"))')"
+decoder_pkg="ds_ctcdecoder-${whl_ds_version}-cp${pyver_pkg}-cp${pyver_pkg}${py_unicode_type}-${platform}.whl"
+
+decoder_pkg_url=${DECODER_ARTIFACTS_ROOT}/${decoder_pkg}
+
+LD_LIBRARY_PATH=${PY37_LDPATH}:$LD_LIBRARY_PATH pip install --verbose --only-binary :all: ${PY37_SOURCE_PACKAGE} ${decoder_pkg_url} | cat
+
+pushd ${HOME}/DeepSpeech/ds/
+    time ./bin/run-tc-transfer.sh
+popd
+
+deactivate

taskcluster/test-transfer-linux-amd64-py36m-opt.yml

@@ -0,0 +1,12 @@
+build:
+  template_file: test-linux-opt-base.tyml
+  dependencies:
+    - "linux-amd64-ctc-opt"
+  system_setup:
+    >
+      apt-get -qq -y install ${python.packages_trusty.apt}
+  args:
+    tests_cmdline: "${system.homedir.linux}/DeepSpeech/ds/taskcluster/tc-transfer-tests.sh 3.6.4:m"
+  metadata:
+    name: "DeepSpeech Linux AMD64 CPU transfer learning Py3.6"
+    description: "Training a DeepSpeech LDC93S1 model with transfer learning for Linux/AMD64 16kHz Python 3.6, CPU only, optimized version"

util/checkpoints.py

@@ -0,0 +1,115 @@
+import sys
+import tensorflow as tf
+import tensorflow.compat.v1 as tfv1
+
+from util.flags import FLAGS
+from util.logging import log_info, log_error, log_warn
+
+
+def _load_checkpoint(session, checkpoint_path):
+    # Load the checkpoint and put all variables into loading list
+    # we will exclude variables we do not wish to load and then
+    # we will initialize them instead
+    ckpt = tfv1.train.load_checkpoint(checkpoint_path)
+    load_vars = set(tfv1.global_variables())
+    init_vars = set()
+
+    if FLAGS.load_cudnn:
+        # Initialize training from a CuDNN RNN checkpoint
+        # Identify the variables which we cannot load, and set them
+        # for initialization
+        for v in load_vars:
+            try:
+                ckpt.get_tensor(v.op.name)
+            except tf.errors.NotFoundError:
+                log_error('CUDNN variable not found: %s' % (v.op.name))
+                init_vars.add(v)
+
+        load_vars -= init_vars
+
+        # Check that the only missing variables (i.e. those to be initialised)
+        # are the Adam moment tensors, if they aren't then we have an issue
+        init_var_names = [v.op.name for v in init_vars]
+        if any('Adam' not in v for v in init_var_names):
+            log_error('Tried to load a CuDNN RNN checkpoint but there were '
+                      'more missing variables than just the Adam moment '
+                      'tensors. Missing variables: {}'.format(init_var_names))
+            sys.exit(1)
+
+    if FLAGS.drop_source_layers > 0:
+        # This transfer learning approach requires supplying
+        # the layers which we exclude from the source model.
+        # Say we want to exclude all layers except for the first one,
+        # then we are dropping five layers total, so: drop_source_layers=5
+        # If we want to use all layers from the source model except
+        # the last one, we use this: drop_source_layers=1
+        if FLAGS.drop_source_layers >= 6:
+            log_warn('The checkpoint only has 6 layers, but you are trying to drop '
+                     'all of them or more than all of them. Continuing and '
+                     'dropping only 5 layers.')
+            FLAGS.drop_source_layers = 5
+
+        dropped_layers = ['2', '3', 'lstm', '5', '6'][-1 * int(FLAGS.drop_source_layers):]
+        # Initialize all variables needed for DS, but not loaded from ckpt
+        for v in load_vars:
+            if any(layer in v.op.name for layer in dropped_layers):
+                init_vars.add(v)
+        load_vars -= init_vars
+
+    for v in sorted(load_vars, key=lambda v: v.op.name):
+        log_info('Loading variable from checkpoint: %s' % (v.op.name))
+        v.load(ckpt.get_tensor(v.op.name), session=session)
+
+    for v in sorted(init_vars, key=lambda v: v.op.name):
+        log_info('Initializing variable: %s' % (v.op.name))
+        session.run(v.initializer)
+
+
+def _checkpoint_path_or_none(checkpoint_filename):
+    checkpoint = tfv1.train.get_checkpoint_state(FLAGS.load_checkpoint_dir, checkpoint_filename)
+    if not checkpoint:
+        return None
+    return checkpoint.model_checkpoint_path
+
+
+def _initialize_all_variables(session):
+    init_vars = tfv1.global_variables()
+    for v in init_vars:
+        session.run(v.initializer)
+
+
+def load_or_init_graph(session, method_order):
+    '''
+    Load variables from checkpoint or initialize variables following the method
+    order specified in the method_order parameter.
+
+    Valid methods are 'best', 'last' and 'init'.
+    '''
+    for method in method_order:
+        # Load best validating checkpoint, saved in checkpoint file 'best_dev_checkpoint'
+        if method == 'best':
+            ckpt_path = _checkpoint_path_or_none('best_dev_checkpoint')
+            if ckpt_path:
+                log_info('Loading best validating checkpoint from {}'.format(ckpt_path))
+                return _load_checkpoint(session, ckpt_path)
+            log_info('Could not find best validating checkpoint.')
+
+        # Load most recent checkpoint, saved in checkpoint file 'checkpoint'
+        elif method == 'last':
+            ckpt_path = _checkpoint_path_or_none('checkpoint')
+            if ckpt_path:
+                log_info('Loading most recent checkpoint from {}'.format(ckpt_path))
+                return _load_checkpoint(session, ckpt_path)
+            log_info('Could not find most recent checkpoint.')
+
+        # Initialize all variables
+        elif method == 'init':
+            log_info('Initializing all variables.')
+            return _initialize_all_variables(session)
+
+        else:
+            log_error('Unknown initialization method: {}'.format(method))
+            sys.exit(1)
+
+    log_error('All initialization methods failed ({}).'.format(method_order))
+    sys.exit(1)

util/config.py

@@ -124,4 +124,21 @@ def initialize_globals():
             log_error('Path specified in --one_shot_infer is not a valid file.')
             sys.exit(1)
 
+    if FLAGS.train_cudnn and FLAGS.load_cudnn:
+        log_error('Trying to use --train_cudnn, but --load_cudnn '
+                  'was also specified. The --load_cudnn flag is only '
+                  'needed when converting a CuDNN RNN checkpoint to '
+                  'a CPU-capable graph. If your system is capable of '
+                  'using CuDNN RNN, you can just specify the CuDNN RNN '
+                  'checkpoint normally with --save_checkpoint_dir.')
+        sys.exit(1)
+
+    # If separate save and load flags were not specified, default to load and save
+    # from the same dir.
+    if not FLAGS.save_checkpoint_dir:
+        FLAGS.save_checkpoint_dir = FLAGS.checkpoint_dir
+
+    if not FLAGS.load_checkpoint_dir:
+        FLAGS.load_checkpoint_dir = FLAGS.checkpoint_dir
+
     ConfigSingleton._config = c # pylint: disable=protected-access

util/flags.py

@@ -49,7 +49,6 @@ def create_flags():
     f.DEFINE_float('augmentation_pitch_and_tempo_scaling_max_pitch', 1.2, 'max value of pitch scaling')
     f.DEFINE_float('augmentation_pitch_and_tempo_scaling_max_tempo', 1.2, 'max vlaue of tempo scaling')
 
-
     # Global Constants
     # ================
 
@@ -84,9 +83,8 @@ def create_flags():
     f.DEFINE_integer('inter_op_parallelism_threads', 0, 'number of inter-op parallelism threads - see tf.ConfigProto for more details. USE OF THIS FLAG IS UNSUPPORTED')
     f.DEFINE_integer('intra_op_parallelism_threads', 0, 'number of intra-op parallelism threads - see tf.ConfigProto for more details. USE OF THIS FLAG IS UNSUPPORTED')
     f.DEFINE_boolean('use_allow_growth', False, 'use Allow Growth flag which will allocate only required amount of GPU memory and prevent full allocation of available GPU memory')
-    f.DEFINE_boolean('use_cudnn_rnn', False, 'use CuDNN RNN backend for training on GPU. Note that checkpoints created with this flag can only be used with CuDNN RNN, i.e. fine tuning on a CPU device will not work')
+    f.DEFINE_boolean('load_cudnn', False, 'Specifying this flag allows one to convert a CuDNN RNN checkpoint to a checkpoint capable of running on a CPU graph.')
-    f.DEFINE_string('cudnn_checkpoint', '', 'path to a checkpoint created using --use_cudnn_rnn. Specifying this flag allows one to convert a CuDNN RNN checkpoint to a checkpoint capable of running on a CPU graph.')
+    f.DEFINE_boolean('train_cudnn', False, 'use CuDNN RNN backend for training on GPU. Note that checkpoints created with this flag can only be used with CuDNN RNN, i.e. fine tuning on a CPU device will not work')
-
     f.DEFINE_boolean('automatic_mixed_precision', False, 'whether to allow automatic mixed precision training. USE OF THIS FLAG IS UNSUPPORTED. Checkpoints created with automatic mixed precision training will not be usable without mixed precision.')
 
     # Sample limits
@@ -97,10 +95,16 @@ def create_flags():
 
     # Checkpointing
 
-    f.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')
+    f.DEFINE_string('checkpoint_dir', '', 'directory from which checkpoints are loaded and to which they are saved - defaults to directory "deepspeech/checkpoints" within user\'s data home specified by the XDG Base Directory Specification')
+    f.DEFINE_string('load_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')
+    f.DEFINE_string('save_checkpoint_dir', '', 'directory to which checkpoints are saved - defaults to directory "deepspeech/checkpoints" within user\'s data home specified by the XDG Base Directory Specification')
     f.DEFINE_integer('checkpoint_secs', 600, 'checkpoint saving interval in seconds')
     f.DEFINE_integer('max_to_keep', 5, 'number of checkpoint files to keep - default value is 5')
-    f.DEFINE_string('load', 'auto', '"last" for loading most recent epoch checkpoint, "best" for loading best validated checkpoint, "init" for initializing a fresh model, "auto" for trying the other options in order last > best > init')
+    f.DEFINE_string('load', 'auto', '"last" for loading most recent epoch checkpoint, "best" for loading best validation loss checkpoint, "init" for initializing a fresh model, "transfer" for transfer learning, "auto" for trying several options.')
+
+    # Transfer Learning
+
+    f.DEFINE_integer('drop_source_layers', 0, 'single integer for how many layers to drop from source model (to drop just output == 1, drop penultimate and output ==2, etc)')
 
     # Exporting
 
@@ -115,7 +119,7 @@ def create_flags():
 
     # Reporting
 
-    f.DEFINE_integer('log_level', 1, 'log level for console logs - 0: INFO, 1: WARN, 2: ERROR, 3: FATAL')
+    f.DEFINE_integer('log_level', 1, 'log level for console logs - 0: DEBUG, 1: INFO, 2: WARN, 3: ERROR')
     f.DEFINE_boolean('show_progressbar', True, 'Show progress for training, validation and testing processes. Log level should be > 0.')
 
     f.DEFINE_boolean('log_placement', False, 'whether to log device placement of the operators to the console')

util/helpers.py

@@ -1,3 +1,7 @@
+import os
+import semver
+import sys
+
 
 def keep_only_digits(txt):
     return ''.join(filter(lambda c: c.isdigit(), txt))
@@ -8,15 +12,12 @@ def secs_to_hours(secs):
     minutes, seconds = divmod(remainder, 60)
     return '%d:%02d:%02d' % (hours, minutes, seconds)
 
-# pylint: disable=import-outside-toplevel
-def check_ctcdecoder_version():
-    import sys
-    import os
-    import semver
 
+def check_ctcdecoder_version():
     ds_version_s = open(os.path.join(os.path.dirname(__file__), '../VERSION')).read().strip()
 
     try:
+        # pylint: disable=import-outside-toplevel
         from ds_ctcdecoder import __version__ as decoder_version
     except ImportError as e:
         if e.msg.find('__version__') > 0: