I've recently started to use Google Colab, and wanted to train my first Convolutional NN. I imported the images from my Google Drive thanks to the answer I got here.
Then I pasted my code to create the CNN into Colab and started the process. Here is the complete code:
(part 1 is copied from here as it worked as exptected for me
Step 1:
!apt-get install -y -qq software-properties-common python-software-properties module-init-tools
!add-apt-repository -y ppa:alessandro-strada/ppa 2>&1 > /dev/null
!apt-get update -qq 2>&1 > /dev/null
!apt-get -y install -qq google-drive-ocamlfuse fuse
Step 2:
from google.colab import auth
auth.authenticate_user()
Step 3:
from oauth2client.client import GoogleCredentials
creds = GoogleCredentials.get_application_default()
import getpass
!google-drive-ocamlfuse -headless -id={creds.client_id} -secret={creds.client_secret} < /dev/null 2>&1 | grep URL
vcode = getpass.getpass()
!echo {vcode} | google-drive-ocamlfuse -headless -id={creds.client_id} -secret={creds.client_secret}
Step 4:
!mkdir -p drive
!google-drive-ocamlfuse drive
Step 5:
print('Files in Drive:')
!ls drive/
I created this CNN with tutorials from a Udemy Course. It uses keras with tensorflow as backend. For the sake of simplicity I uploaded a really simple version, which is plenty enough to show my problems
from keras.models import Sequential
from keras.layers import Conv2D
from keras.layers import MaxPooling2D
from keras.layers import Flatten
from keras.layers import Dense
from keras.layers import Dropout
from keras.optimizers import Adam
from keras.preprocessing.image import ImageDataGenerator
parameters
imageSize=32
batchSize=64
epochAmount=50
CNN
classifier=Sequential()
classifier.add(Conv2D(32, (3, 3), input_shape = (imageSize, imageSize, 3), activation = 'relu')) #convolutional layer
classifier.add(MaxPooling2D(pool_size = (2, 2))) #pooling layer
classifier.add(Flatten())
ANN
classifier.add(Dense(units=64, activation='relu')) #hidden layer
classifier.add(Dense(units=1, activation='sigmoid')) #output layer
classifier.compile(optimizer = "adam", loss = 'binary_crossentropy', metrics = ['accuracy']) #training method
image preprocessing
train_datagen = ImageDataGenerator(rescale = 1./255,
shear_range = 0.2,
zoom_range = 0.2,
horizontal_flip = True)
test_datagen = ImageDataGenerator(rescale = 1./255)
training_set = train_datagen.flow_from_directory('drive/School/sem-2-2018/BSP2/UdemyCourse/CNN/dataset/training_set',
target_size = (imageSize, imageSize),
batch_size = batchSize,
class_mode = 'binary')
test_set = test_datagen.flow_from_directory('drive/School/sem-2-2018/BSP2/UdemyCourse/CNN/dataset/test_set',
target_size = (imageSize, imageSize),
batch_size = batchSize,
class_mode = 'binary')
classifier.fit_generator(training_set,
steps_per_epoch = (8000//batchSize),
epochs = epochAmount,
validation_data = test_set,
validation_steps = (2000//batchSize))
First of, the training set I used is a database with 10000 dog and cat pictures of various resolutions. (8000 training_set, 2000 test_set)
I ran this CNN on Google Colab (with GPU support enabled) and on my PC (tensorflow-gpu on GTX 1060)
This is an intermediate result from my PC:
Epoch 2/50
63/125 [==============>...............] - ETA: 2s - loss: 0.6382 - acc: 0.6520
And this from Colab:
Epoch 1/50
13/125 [==>...........................] - ETA: 1:00:51 - loss: 0.7265 - acc: 0.4916
Why is Google Colab so slow in my case?
Personally I suspect a bottleneck consisting of pulling and then reading the images from my Drive, but I don't know how to solve this other than choosing a different method to import the database.
As @Feng has already noted, reading files from drive is very slow. This tutorial suggests using some sort of a memory mapped file like hdf5 or lmdb in order to overcome this issue. This way the I\O Operations are much faster (for a complete explanation on the speed gain of hdf5 format see this).