1 files changed, 6 insertions, 0 deletions
diff --git a/Lib/asyncio/streams.py b/Lib/asyncio/streams.py
index bf15f517e50..b7ad365709b 100644
--- a/Lib/asyncio/streams.py
+++ b/Lib/asyncio/streams.py
@@ -5,6 +5,7 @@ __all__ = (
 import collections
 import socket
 import sys
+import warnings
 import weakref
 
 if hasattr(socket, 'AF_UNIX'):
@@ -392,6 +393,11 @@ class StreamWriter:
         self._transport = new_transport
         protocol._replace_writer(self)
 
+    def __del__(self, warnings=warnings):
+        if not self._transport.is_closing():
+            self.close()
+            warnings.warn(f"unclosed {self!r}", ResourceWarning)
+
 
 class StreamReader: