diff --git a/deepspeech/training/cli.py b/deepspeech/training/cli.py
index ecd7a8f267e536e708fc4aea5eaba695780f359d..7f4bb804832a1df7dcfabf8fb48ee39ddaed8d5a 100644
--- a/deepspeech/training/cli.py
+++ b/deepspeech/training/cli.py
@@ -64,7 +64,7 @@ def default_argument_parser():
                         help="options to overwrite --config file and the default config, passing in KEY VALUE pairs")
 
     parser.add_argument("--seed", type=int, default=None,
-                        help="seed to use for paddle, np and random. The default value is None")
+                        help="seed to use for paddle, np and random. None or 0 for random, else set seed.")
     # yapd: enable
 
     return parser
diff --git a/deepspeech/training/extensions/__init__.py b/deepspeech/training/extensions/__init__.py
index 7ea7470eedfc4d32de9670e761438af146cc19be..6ad04155931b1071c6fe746c3befaf07bda91051 100644
--- a/deepspeech/training/extensions/__init__.py
+++ b/deepspeech/training/extensions/__init__.py
@@ -1,8 +1,21 @@
-
+# Copyright (c) 2021 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
+# limitations under the License.
 from typing import Callable
 
 from .extension import Extension
 
+
 def make_extension(trigger: Callable=None,
                    default_name: str=None,
                    priority: int=None,
@@ -25,4 +38,4 @@ def make_extension(trigger: Callable=None,
         ext.initialize = initializer
         return ext
 
-    return decorator
\ No newline at end of file
+    return decorator
diff --git a/deepspeech/training/extensions/evaluator.py b/deepspeech/training/extensions/evaluator.py
index ffb7b3a246981cb1f1d5bb07857b652324bb442e..96ff967f53a14203d313aaf024799d95b6fd307f 100644
--- a/deepspeech/training/extensions/evaluator.py
+++ b/deepspeech/training/extensions/evaluator.py
@@ -1,10 +1,23 @@
+# Copyright (c) 2021 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
+# limitations under the License.
 from typing import Dict
 
+import extension
 import paddle
 from paddle.io import DataLoader
 from paddle.nn import Layer
 
-import extension
 from ..reporter import DictSummary
 from ..reporter import report
 from ..reporter import scope
@@ -55,4 +68,4 @@ class StandardEvaluator(extension.Extension):
         # or otherwise, you can use your own observation
         summary = self.evaluate()
         for k, v in summary.items():
-            report(k, v)
\ No newline at end of file
+            report(k, v)
diff --git a/deepspeech/training/extensions/extension.py b/deepspeech/training/extensions/extension.py
index f8fcede3fe728b0eccc485e1e55e51c0d33f02be..02f924951304a5c83e4354297f12919033dc265b 100644
--- a/deepspeech/training/extensions/extension.py
+++ b/deepspeech/training/extensions/extension.py
@@ -1,5 +1,16 @@
-from typing import Callable
-
+# Copyright (c) 2021 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
+# limitations under the License.
 PRIORITY_WRITER = 300
 PRIORITY_EDITOR = 200
 PRIORITY_READER = 100
@@ -38,4 +49,4 @@ class Extension():
         """Action that is executed when training is done.
         For example, visualizers would need to be closed.
         """
-        pass
\ No newline at end of file
+        pass
diff --git a/deepspeech/training/extensions/snapshot.py b/deepspeech/training/extensions/snapshot.py
index a15537a05eb27bd7ea37dff7393fa8e7e0393c61..cb4e6dfbff84d4dfed91af599b1bb040f37e9660 100644
--- a/deepspeech/training/extensions/snapshot.py
+++ b/deepspeech/training/extensions/snapshot.py
@@ -1,3 +1,16 @@
+# Copyright (c) 2021 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
+# limitations under the License.
 import os
 from datetime import datetime
 from pathlib import Path
@@ -7,11 +20,10 @@ from typing import List
 
 import jsonlines
 
-from deepspeech.training.updaters.trainer import Trainer
 from deepspeech.training.extensions import extension
-from deepspeech.utils.mp_tools import rank_zero_only
-
+from deepspeech.training.updaters.trainer import Trainer
 from deepspeech.utils.log import Log
+from deepspeech.utils.mp_tools import rank_zero_only
 
 logger = Log(__name__).getlog()
 
@@ -75,7 +87,7 @@ class Snapshot(extension.Extension):
         """Saving new snapshot and remove the oldest snapshot if needed."""
         iteration = trainer.updater.state.iteration
         epoch = trainer.updater.state.epoch
-        num = epoch if self.trigger[1] is 'epoch' else iteration
+        num = epoch if self.trigger[1] == 'epoch' else iteration
         path = self.checkpoint_dir / f"{num}.pdz"
 
         # add the new one
@@ -99,4 +111,4 @@ class Snapshot(extension.Extension):
         with jsonlines.open(record_path, 'w') as writer:
             for record in self.records:
                 # jsonlines.open may return a Writer or a Reader
-                writer.write(record)  # pylint: disable=no-member
\ No newline at end of file
+                writer.write(record)  # pylint: disable=no-member
diff --git a/deepspeech/training/extensions/visualizer.py b/deepspeech/training/extensions/visualizer.py
index 92e07704a51c6aabfee18f6d092e358079f5c311..b69e94aaf4bbd42bb1bb50010af86e419d7c7ddb 100644
--- a/deepspeech/training/extensions/visualizer.py
+++ b/deepspeech/training/extensions/visualizer.py
@@ -1,3 +1,16 @@
+# Copyright (c) 2021 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
+# limitations under the License.
 from deepspeech.training.extensions import extension
 from deepspeech.training.updaters.trainer import Trainer
 
@@ -21,4 +34,4 @@ class VisualDL(extension.Extension):
             self.writer.add_scalar(k, v, step=trainer.updater.state.iteration)
 
     def finalize(self, trainer):
-        self.writer.close()
\ No newline at end of file
+        self.writer.close()
diff --git a/deepspeech/training/reporter.py b/deepspeech/training/reporter.py
index a5f79fb0e711d363f9158aa6382149189d03966b..66a81adef1c47f8fe55ad8d608daaa2cb97545ff 100644
--- a/deepspeech/training/reporter.py
+++ b/deepspeech/training/reporter.py
@@ -1,3 +1,16 @@
+# Copyright (c) 2021 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
+# limitations under the License.
 import contextlib
 import math
 from collections import defaultdict
@@ -128,4 +141,4 @@ class DictSummary():
             stats[name] = mean
             stats[name + '.std'] = std
 
-        return stats
\ No newline at end of file
+        return stats
diff --git a/deepspeech/training/trainer.py b/deepspeech/training/trainer.py
index 866be552da1537ac5a32720b1fdb3cbd35e7509b..3a922c6f4f88f03dadf20e8e978a84bcf436a58a 100644
--- a/deepspeech/training/trainer.py
+++ b/deepspeech/training/trainer.py
@@ -11,11 +11,9 @@
 # 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 random
 import time
 from pathlib import Path
 
-import numpy as np
 import paddle
 from paddle import distributed as dist
 from tensorboardX import SummaryWriter
@@ -23,6 +21,7 @@ from tensorboardX import SummaryWriter
 from deepspeech.utils import mp_tools
 from deepspeech.utils.checkpoint import Checkpoint
 from deepspeech.utils.log import Log
+from deepspeech.utils.utility import seed_all
 
 __all__ = ["Trainer"]
 
@@ -95,13 +94,10 @@ class Trainer():
         self.checkpoint_dir = None
         self.iteration = 0
         self.epoch = 0
-        if args.seed is not None:
-            self.set_seed(args.seed)
 
-    def set_seed(self, seed):
-        np.random.seed(seed)
-        random.seed(seed)
-        paddle.seed(seed)
+        if args.seed:
+            seed_all(args.seed)
+            logger.info(f"Set seed {args.seed}")
 
     def setup(self):
         """Setup the experiment.
@@ -182,7 +178,9 @@ class Trainer():
         """
         self.epoch += 1
         if self.parallel and hasattr(self.train_loader, "batch_sampler"):
-            self.train_loader.batch_sampler.set_epoch(self.epoch)
+            batch_sampler = self.train_loader.batch_sampler
+            if isinstance(batch_sampler, paddle.io.DistributedBatchSampler):
+                batch_sampler.set_epoch(self.epoch)
 
     def train(self):
         """The training process control by epoch."""
diff --git a/deepspeech/training/triggers/__init__.py b/deepspeech/training/triggers/__init__.py
index 9da7e6153a8d4cb4fd2208dd2ba02cdaac5d9dab..1a7c4292e6e1f81e4a34efb517c05f58c5d8f1fe 100644
--- a/deepspeech/training/triggers/__init__.py
+++ b/deepspeech/training/triggers/__init__.py
@@ -1,8 +1,23 @@
+# Copyright (c) 2021 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
+# limitations under the License.
 from .interval_trigger import IntervalTrigger
 
+
 def never_fail_trigger(trainer):
     return False
 
+
 def get_trigger(trigger):
     if trigger is None:
         return never_fail_trigger
@@ -10,4 +25,4 @@ def get_trigger(trigger):
         return trigger
     else:
         trigger = IntervalTrigger(*trigger)
-        return trigger
\ No newline at end of file
+        return trigger
diff --git a/deepspeech/training/triggers/interval_trigger.py b/deepspeech/training/triggers/interval_trigger.py
index ef80379cb8f8aa42c41c43ea1a51b16b6b14ad0f..1e04afad8d52ba6a8a272edebfba7f09f9784723 100644
--- a/deepspeech/training/triggers/interval_trigger.py
+++ b/deepspeech/training/triggers/interval_trigger.py
@@ -1,3 +1,17 @@
+# Copyright (c) 2021 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
+# limitations under the License.
+
 
 class IntervalTrigger():
     """A Predicate to do something every N cycle."""
@@ -21,4 +35,4 @@ class IntervalTrigger():
         fire = index // self.period != last_index // self.period
 
         self.last_index = index
-        return fire
\ No newline at end of file
+        return fire
diff --git a/deepspeech/training/triggers/limit_trigger.py b/deepspeech/training/triggers/limit_trigger.py
index ce13f940a8c3510676b1ccc55a628c2c8795b39d..ecd527ac5349486fa398c00e1171d8d1b51b293b 100644
--- a/deepspeech/training/triggers/limit_trigger.py
+++ b/deepspeech/training/triggers/limit_trigger.py
@@ -1,3 +1,17 @@
+# Copyright (c) 2021 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
+# limitations under the License.
+
 
 class LimitTrigger():
     """A Predicate to decide whether to stop."""
@@ -14,4 +28,4 @@ class LimitTrigger():
         state = trainer.updater.state
         index = getattr(state, self.unit)
         fire = index >= self.limit
-        return fire
\ No newline at end of file
+        return fire
diff --git a/deepspeech/training/triggers/time_trigger.py b/deepspeech/training/triggers/time_trigger.py
index 6232a12d3bcd728ed5004ccac054619afba0fa4f..ea8fe562c7f67a6732e88fda3518fcc526596a20 100644
--- a/deepspeech/training/triggers/time_trigger.py
+++ b/deepspeech/training/triggers/time_trigger.py
@@ -1,3 +1,18 @@
+# Copyright (c) 2021 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
+# limitations under the License.
+
+
 class TimeTrigger():
     """Trigger based on a fixed time interval.
     This trigger accepts iterations with a given interval time.
@@ -14,4 +29,4 @@ class TimeTrigger():
             self._next_time += self._period
             return True
         else:
-            return False
\ No newline at end of file
+            return False
diff --git a/deepspeech/training/updaters/__init__.py b/deepspeech/training/updaters/__init__.py
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..185a92b8d94d3426d616c0624f0f2ee04339349e 100644
--- a/deepspeech/training/updaters/__init__.py
+++ b/deepspeech/training/updaters/__init__.py
@@ -0,0 +1,13 @@
+# Copyright (c) 2021 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
+# limitations under the License.
diff --git a/deepspeech/training/updaters/standard_updater.py b/deepspeech/training/updaters/standard_updater.py
index 062029ff78eca051b0d5f596aa5ef773078cd817..fc758e93e7390694a1bbd26763db4c941ebc85dd 100644
--- a/deepspeech/training/updaters/standard_updater.py
+++ b/deepspeech/training/updaters/standard_updater.py
@@ -1,3 +1,16 @@
+# Copyright (c) 2021 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
+# limitations under the License.
 from typing import Dict
 from typing import Optional
 
@@ -11,13 +24,13 @@ from timer import timer
 from deepspeech.training.reporter import report
 from deepspeech.training.updaters.updater import UpdaterBase
 from deepspeech.training.updaters.updater import UpdaterState
-
 from deepspeech.utils.log import Log
 
 __all__ = ["StandardUpdater"]
 
 logger = Log(__name__).getlog()
 
+
 class StandardUpdater(UpdaterBase):
     """An example of over-simplification. Things may not be that simple, but
     you can subclass it to fit your need.
@@ -142,7 +155,7 @@ class StandardUpdater(UpdaterBase):
         """Start a new epoch."""
         # NOTE: all batch sampler for distributed training should
         # subclass DistributedBatchSampler and implement `set_epoch` method
-        if hasattr(self.dataloader, "batch_sampler")
+        if hasattr(self.dataloader, "batch_sampler"):
             batch_sampler = self.dataloader.batch_sampler
             if isinstance(batch_sampler, DistributedBatchSampler):
                 batch_sampler.set_epoch(self.state.epoch)
@@ -176,4 +189,4 @@ class StandardUpdater(UpdaterBase):
             model.set_state_dict(state_dict[f"{name}_params"])
         for name, optim in self.optimizers.items():
             optim.set_state_dict(state_dict[f"{name}_optimizer"])
-        super().set_state_dict(state_dict)
\ No newline at end of file
+        super().set_state_dict(state_dict)
diff --git a/deepspeech/training/updaters/trainer.py b/deepspeech/training/updaters/trainer.py
index c7562ff06c07123f26b49947a399229f8676119a..954ce2604d18569b34c35be4fd517f74a59fc14e 100644
--- a/deepspeech/training/updaters/trainer.py
+++ b/deepspeech/training/updaters/trainer.py
@@ -1,3 +1,16 @@
+# Copyright (c) 2021 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
+# limitations under the License.
 import sys
 import traceback
 from collections import OrderedDict
@@ -168,4 +181,4 @@ class Trainer():
         finally:
             for name, entry in extensions:
                 if hasattr(entry.extension, "finalize"):
-                    entry.extension.finalize(self)
\ No newline at end of file
+                    entry.extension.finalize(self)
diff --git a/deepspeech/training/updaters/updater.py b/deepspeech/training/updaters/updater.py
index 548042d6a8e0e48e8445afd514cbc290309ad8d0..66fdc2bbc7aea7b7f08f1423a58736e6ffb3b068 100644
--- a/deepspeech/training/updaters/updater.py
+++ b/deepspeech/training/updaters/updater.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 from dataclasses import dataclass
+
 import paddle
 
 from deepspeech.utils.log import Log
@@ -79,4 +80,4 @@ class UpdaterBase():
     def load(self, path):
         logger.debug(f"Loading from {path}.")
         archive = paddle.load(str(path))
-        self.set_state_dict(archive)
\ No newline at end of file
+        self.set_state_dict(archive)
diff --git a/deepspeech/utils/utility.py b/deepspeech/utils/utility.py
index a0639e0654faec299bb7353b950b122ee0103167..e18fc1f775fc1281dbcd05ecd25bc3de6d1cbef1 100644
--- a/deepspeech/utils/utility.py
+++ b/deepspeech/utils/utility.py
@@ -15,9 +15,19 @@
 import distutils.util
 import math
 import os
+import random
 from typing import List
 
-__all__ = ['print_arguments', 'add_arguments', "log_add"]
+import numpy as np
+import paddle
+
+__all__ = ["seed_all", 'print_arguments', 'add_arguments', "log_add"]
+
+
+def seed_all(seed: int=210329):
+    np.random.seed(seed)
+    random.seed(seed)
+    paddle.seed(seed)
 
 
 def print_arguments(args, info=None):
diff --git a/examples/aishell/s0/README.md b/examples/aishell/s0/README.md
index eedf92c963bbad7d06c12c5fd661ca4b18abd9c5..537496a6781840a6091931f6c5c7e30f1b109a83 100644
--- a/examples/aishell/s0/README.md
+++ b/examples/aishell/s0/README.md
@@ -3,11 +3,9 @@
 ## Data
 | Data Subset | Duration in Seconds |
 | data/manifest.train |  1.23 ~ 14.53125 |
-| data/manifest.dev | 1.645 ~ 12.533 |  
+| data/manifest.dev  | 1.645 ~ 12.533 |  
 | data/manifest.test | 1.859125 ~ 14.6999375 |
 
-`jq '.feat_shape[0]' data/manifest.train | sort -un`
-
 ## Deepspeech2
 
 | Model | Params | Release | Config | Test set | Loss | CER |  
diff --git a/requirements.txt b/requirements.txt
index 1ed5525ea6f5e2e964ba3cb81234b46adf46095b..7c3da37e131064d0327e728d115103d7e34da192 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,6 @@
 coverage
 gpustat
+jsonlines
 kaldiio
 Pillow
 pre-commit
@@ -15,4 +16,3 @@ tensorboardX
 textgrid
 typeguard
 yacs
-jsonlines
\ No newline at end of file