Python issue #23243: On Python 3.4 and newer, emit a ResourceWarning when anHEADmaster

event loop or a transport is not explicitly closed

1 files changed, 11 insertions, 0 deletions

diff --git a/asyncio/proactor_events.py b/asyncio/proactor_events.py
index 0f533a5..65de926 100644
--- a/asyncio/proactor_events.py
+++ b/asyncio/proactor_events.py
@@ -7,6 +7,8 @@ proactor is only implemented on Windows with IOCP.
 __all__ = ['BaseProactorEventLoop']
 
 import socket
+import sys
+import warnings
 
 from . import base_events
 from . import constants
@@ -74,6 +76,15 @@ class _ProactorBasePipeTransport(transports._FlowControlMixin,
             self._read_fut.cancel()
             self._read_fut = None
 
+    # On Python 3.3 and older, objects with a destructor part of a reference
+    # cycle are never destroyed. It's not more the case on Python 3.4 thanks
+    # to the PEP 442.
+    if sys.version_info >= (3, 4):
+        def __del__(self):
+            if self._sock is not None:
+                warnings.warn("unclosed transport %r" % self, ResourceWarning)
+                self.close()
+
     def _fatal_error(self, exc, message='Fatal error on pipe transport'):
         if isinstance(exc, (BrokenPipeError, ConnectionResetError)):
             if self._loop.get_debug():