fixes logger crash on ddp (#2388)

* remove warnings

* remove warnings

* remove warnings

* remove warnings

* remove warnings

* remove warnings

* remove warnings

* remove warnings

* remove warnings

* remove warnings

Author: williamFalcon

pl_examples/models/lightning_template.py

@@ -150,15 +150,12 @@ def setup(self, stage):
         self.mnist_test = MNIST(self.data_root, train=False, download=False, transform=transform)
 
     def train_dataloader(self):
-        log.info('Training data loader called.')
         return DataLoader(self.mnist_train, batch_size=self.batch_size, num_workers=4)
 
     def val_dataloader(self):
-        log.info('Validation data loader called.')
         return DataLoader(self.mnist_test, batch_size=self.batch_size, num_workers=4)
 
     def test_dataloader(self):
-        log.info('Test data loader called.')
         return DataLoader(self.mnist_test, batch_size=self.batch_size, num_workers=4)
 
     @staticmethod

pytorch_lightning/trainer/callback_config.py

@@ -42,7 +42,7 @@ def configure_checkpoint_callback(self):
         ckpt_path = self.default_root_dir
         if self.checkpoint_callback:
             # init a default one
-            if self.logger is not None:
+            if self.logger is not None and self.logger.experiment is not None:
                 save_dir = (getattr(self.logger, 'save_dir', None) or
                             getattr(self.logger, '_save_dir', None) or
                             self.default_root_dir)
@@ -53,12 +53,7 @@ def configure_checkpoint_callback(self):
 
                 version = self.logger.version if isinstance(
                     self.logger.version, str) else f'version_{self.logger.version}'
-                ckpt_path = os.path.join(
-                    save_dir,
-                    self.logger.name,
-                    version,
-                    "checkpoints"
-                )
+                ckpt_path = os.path.join(save_dir, self.logger.name, version, "checkpoints")
             else:
                 ckpt_path = os.path.join(self.default_root_dir, "checkpoints")