Composer object store download retry

composer/utils/checkpoint.py

@@ -39,6 +39,7 @@
 )
 from composer.utils.misc import is_model_deepspeed, partial_format
 from composer.utils.object_store import ObjectStore
+from composer.utils.retrying import retry
 
 if TYPE_CHECKING:
     from composer.core import AlgorithmPass, State
@@ -188,6 +189,24 @@ def read_metadata(self) -> Metadata:
         return super().read_metadata()
 
 
+@retry(num_attempts=5)
+def download_object_or_file(
+    object_name: str,
+    file_destination: Union[str, Path],
+    object_store: Union[ObjectStore, LoggerDestination],
+):
+    if isinstance(object_store, ObjectStore):
+        object_store.download_object(
+            object_name=object_name,
+            filename=file_destination,
+        )
+    else:
+        object_store.download_file(
+            remote_file_name=object_name,
+            destination=str(file_destination),
+        )
+
+
 # A subclass of FileSystemReaderWithValidation that downloads files from the object store before reading them from the local filesystem.
 class DistCPObjectStoreReader(FileSystemReaderWithValidation):
 
@@ -262,16 +281,7 @@ def read_data(self, plan: LoadPlan, planner: LoadPlanner):
                     if not is_downloaded and not os.path.exists(file_destination):
                         log.debug(f'Downloading {relative_file_path} to {file_destination}.')
                         object_name = str(Path(self.source_path) / Path(relative_file_path))
-                        if isinstance(self.object_store, ObjectStore):
-                            self.object_store.download_object(
-                                object_name=object_name,
-                                filename=file_destination,
-                            )
-                        else:
-                            self.object_store.download_file(
-                                remote_file_name=object_name,
-                                destination=file_destination,
-                            )
+                        download_object_or_file(object_name, file_destination, self.object_store)
                         log.debug(f'Finished downloading {relative_file_path} to {file_destination}.')
             except Exception as e:
                 # PyTorch will capture any exception of this function,

composer/utils/retrying.py

@@ -7,6 +7,7 @@
 
 import collections.abc
 import functools
+import logging
 import random
 import time
 from typing import Any, Callable, Sequence, Type, TypeVar, Union, cast, overload
@@ -15,6 +16,8 @@
 
 __all__ = ['retry']
 
+log = logging.getLogger(__name__)
+
 
 @overload
 def retry(
@@ -86,6 +89,7 @@ def new_func(*args: Any, **kwargs: Any):
                 try:
                     return func(*args, **kwargs)
                 except exc_class as e:
+                    log.debug(f'Attempt {i} failed. Exception type: {type(e)}, message: {str(e)}.')
                     if i + 1 == num_attempts:
                         raise e
                     else: