Fix slow performance with S3 jazzband#662 jazzband#301 jazzband#508

sorl/thumbnail/images.py

@@ -2,6 +2,7 @@
 import os
 import platform
 import re
+from functools import lru_cache
 from urllib.error import URLError
 from urllib.parse import quote, quote_plus, urlsplit, urlunsplit
 from urllib.request import urlopen, Request
@@ -19,6 +20,11 @@
 url_pat = re.compile(r'^(https?|ftp):\/\/')
 
 
+@lru_cache
+def get_or_create_storage(storage):
+    return get_module_class(storage)()
+
+
 def serialize_image_file(image_file):
     if image_file.size is None:
         raise ThumbnailError('Trying to serialize an ``ImageFile`` with a '
@@ -33,12 +39,7 @@ def serialize_image_file(image_file):
 
 def deserialize_image_file(s):
     data = deserialize(s)
-
-    class LazyStorage(LazyObject):
-        def _setup(self):
-            self._wrapped = get_module_class(data['storage'])()
-
-    image_file = ImageFile(data['name'], LazyStorage())
+    image_file = ImageFile(data['name'], get_or_create_storage(data['storage']))
     image_file.set_size(data['size'])
     return image_file