1 files changed, 23 insertions, 3 deletions
diff --git a/PCbuild/get_external.py b/PCbuild/get_external.py
index 4ecc8925349..a78aa6a2304 100755
--- a/PCbuild/get_external.py
+++ b/PCbuild/get_external.py
@@ -5,8 +5,28 @@ import os
 import pathlib
 import sys
 import time
+import urllib.error
+import urllib.request
 import zipfile
-from urllib.request import urlretrieve
+
+
+def retrieve_with_retries(download_location, output_path, reporthook,
+                          max_retries=7):
+    """Download a file with exponential backoff retry and save to disk."""
+    for attempt in range(max_retries + 1):
+        try:
+            resp = urllib.request.urlretrieve(
+                download_location,
+                output_path,
+                reporthook=reporthook,
+            )
+        except (urllib.error.URLError, ConnectionError) as ex:
+            if attempt == max_retries:
+                msg = f"Download from {download_location} failed."
+                raise OSError(msg) from ex
+            time.sleep(2.25**attempt)
+        else:
+            return resp
 
 
 def fetch_zip(commit_hash, zip_dir, *, org='python', binary=False, verbose):
@@ -16,10 +36,10 @@ def fetch_zip(commit_hash, zip_dir, *, org='python', binary=False, verbose):
     if verbose:
         reporthook = print
     zip_dir.mkdir(parents=True, exist_ok=True)
-    filename, headers = urlretrieve(
+    filename, _headers = retrieve_with_retries(
         url,
         zip_dir / f'{commit_hash}.zip',
-        reporthook=reporthook,
+        reporthook
     )
     return filename