training.py

model = Unet(backbone_name = 'efficientnetb0', encoder_weights='imagenet', encoder_freeze = False)
model.compile(optimizer = Adam(), loss=bce_jaccard_loss, metrics=[iou_score])

history = model.fit_generator(train_generator, shuffle =True,
                  epochs=50, workers=4, use_multiprocessing=True,
                  validation_data = test_generator, 
                  verbose = 1, callbacks=callbacks)