fixing Win failed import (#1163)

* version

* try fix distrib

* update try import

pytorch_lightning/trainer/auto_mix_precision.py

@@ -1,13 +1,12 @@
-
+import logging as log
 from abc import ABC
 
 try:
     from apex import amp
-
-    APEX_AVAILABLE = True
 except ImportError:
     APEX_AVAILABLE = False
-import logging as log
+else:
+    APEX_AVAILABLE = True
 
 
 class TrainerAMPMixin(ABC):

pytorch_lightning/trainer/data_loading.py

@@ -1,7 +1,7 @@
 from abc import ABC, abstractmethod
 from typing import Union, List, Tuple, Callable
 
-import torch.distributed as dist
+import torch.distributed as torch_distrib
 from torch.utils.data import SequentialSampler, DataLoader
 from torch.utils.data.distributed import DistributedSampler
 
@@ -224,7 +224,7 @@ class TrainerDataLoadingMixin(ABC):
         # get the function we'll use to get data
         if self.use_ddp or self.use_ddp2:
             # all processes wait until data download has happened
-            dist.barrier()
+            torch_distrib.barrier()
 
         # data download/load on TPU
         elif self.use_tpu and XLA_AVAILABLE:

pytorch_lightning/trainer/trainer.py

@@ -8,7 +8,7 @@ from typing import Union, Optional, List, Dict, Tuple, Iterable
 
 import torch
 from torch import optim
-import torch.distributed as dist
+import torch.distributed as torch_distrib
 import torch.multiprocessing as mp
 from torch.optim.optimizer import Optimizer
 from torch.utils.data import DataLoader
@@ -748,7 +748,7 @@ class Trainer(
             self.logger.save()
 
         if self.use_ddp or self.use_ddp2:
-            dist.barrier()
+            torch_distrib.barrier()
 
         # wait for all models to restore weights
         if self.on_tpu and XLA_AVAILABLE:

pytorch_lightning/trainer/training_io.py

@@ -100,7 +100,7 @@ from subprocess import call
 from typing import Union
 
 import torch
-import torch.distributed as dist
+import torch.distributed as torch_distrib
 
 from pytorch_lightning.core.lightning import LightningModule
 from pytorch_lightning.loggers import LightningLoggerBase
@@ -177,7 +177,7 @@ class TrainerIOMixin(ABC):
         # wait for all models to restore weights
         if self.use_ddp or self.use_ddp2:
             # wait for all processes to catch up
-            dist.barrier()
+            torch_distrib.barrier()
 
         # wait for all models to restore weights
         if self.on_tpu and XLA_AVAILABLE: