Avoid file not found

Author: carmocca

pl_examples/__init__.py

@@ -14,7 +14,7 @@
 _PACKAGE_ROOT = os.path.dirname(_EXAMPLES_ROOT)
 _DATASETS_PATH = os.path.join(_PACKAGE_ROOT, 'Datasets')
 
-_TORCHVISION_MNIST_AVAILABLE = not bool(os.environ.get("PL_USE_MOCKED_MNIST", False))
+_TORCHVISION_MNIST_AVAILABLE = not bool(os.getenv("PL_USE_MOCKED_MNIST", False))
 _DALI_AVAILABLE = _module_available("nvidia.dali")
 
 if _TORCHVISION_MNIST_AVAILABLE:
@@ -23,6 +23,13 @@
         MNIST(_DATASETS_PATH, download=True)
     except HTTPError:
         _TORCHVISION_MNIST_AVAILABLE = False
+    except RuntimeError as e:
+        # `torchvision` can produce the following error randomly.
+        # File "/usr/local/lib/python3.7/dist-packages/torchvision/datasets/utils.py", line 145, in download_url
+        #   raise RuntimeError("File not found or corrupted.")
+        if "File not found" not in e:
+            raise
+        _TORCHVISION_MNIST_AVAILABLE = False
 
 LIGHTNING_LOGO = """
                     ####