Use high progress_bar_refresh_rate on Google Colab (#4654)

* Use high refresh rate on Google Colab (#3786)

Automatically override progress_bar_refresh_rate when on Google
Colab. Also added a constant IS_COLAB in utilities to check
whether it is being run in colab or not.
(#3786)

* Show a warning instead of overriding when rate is low on colab

* Change warning to suggestion and move it

Moved warning to configure_progress_bar instead of on_trainer_init

* Apply suggestions from code review

Co-authored-by: Rohit Gupta <rohitgr1998@gmail.com>

* add a mock test

Co-authored-by: chaton <thomas@grid.ai>
Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>
Co-authored-by: Rohit Gupta <rohitgr1998@gmail.com>

(cherry picked from commit ccf38ce)

CHANGELOG.md

@@ -12,6 +12,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Added casting to python types for numpy scalars when logging hparams ([#4647](https://github.com/PyTorchLightning/pytorch-lightning/pull/4647))
 
 
+- Added warning when progress bar refresh rate is less than 20 on Google Colab to prevent crashing ([#4654](https://github.com/PyTorchLightning/pytorch-lightning/pull/4654))
+
+
 - Added `F1` class metric ([#4656](https://github.com/PyTorchLightning/pytorch-lightning/pull/4656))
 
 

pytorch_lightning/trainer/connectors/callback_connector.py

@@ -12,10 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import os
+from typing import Optional, Union
 
-from typing import Union, Optional
-
-from pytorch_lightning.callbacks import ModelCheckpoint, EarlyStopping, ProgressBarBase, ProgressBar
+from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint, ProgressBar, ProgressBarBase
 from pytorch_lightning.utilities import rank_zero_warn
 from pytorch_lightning.utilities.exceptions import MisconfigurationException
 
@@ -74,6 +73,14 @@ def configure_checkpoint_callbacks(self, checkpoint_callback: Union[ModelCheckpo
             self.trainer.callbacks.append(ModelCheckpoint(dirpath=None, filename=None))
 
     def configure_progress_bar(self, refresh_rate=1, process_position=0):
+        # smaller refresh rate on colab causes crashes, warn user about this
+        if os.getenv('COLAB_GPU') and refresh_rate < 20:
+            rank_zero_warn(
+                "You have set progress_bar_refresh_rate < 20 on Google Colab. This"
+                " may crash. Consider using progress_bar_refresh_rate >= 20 in Trainer.",
+                UserWarning
+            )
+
         progress_bars = [c for c in self.trainer.callbacks if isinstance(c, ProgressBarBase)]
         if len(progress_bars) > 1:
             raise MisconfigurationException(

pytorch_lightning/utilities/__init__.py

@@ -18,7 +18,7 @@
 import torch
 
 from pytorch_lightning.utilities.apply_func import move_data_to_device
-from pytorch_lightning.utilities.distributed import rank_zero_only, rank_zero_warn, rank_zero_info
+from pytorch_lightning.utilities.distributed import rank_zero_info, rank_zero_only, rank_zero_warn
 from pytorch_lightning.utilities.parsing import AttributeDict, flatten_dict, is_picklable
 
 try:

tests/callbacks/test_progress_bar.py

@@ -11,7 +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 os
 import pytest
+from unittest import mock
 
 from pytorch_lightning import Trainer
 from pytorch_lightning.callbacks import ProgressBarBase, ProgressBar, ModelCheckpoint
@@ -239,3 +241,14 @@ def on_validation_epoch_end(self, trainer, pl_module):
     )
     trainer.fit(model)
     assert trainer.progress_bar_callback.val_progress_bar_total == expected
+
+
+@mock.patch.dict(os.environ, {'COLAB_GPU': '1'})
+def test_progress_bar_warning_on_colab(tmpdir):
+    with pytest.warns(UserWarning, match='on Google Colab. This may crash.'):
+        trainer = Trainer(
+            default_root_dir=tmpdir,
+            progress_bar_refresh_rate=19,
+        )
+
+    assert trainer.progress_bar_callback.refresh_rate == 19