python · 1st1 · May 29, 2018 · May 29, 2018
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
@@ -1106,10 +1106,13 @@ async def start_tls(self, transport, protocol, sslcontext, *,
             ssl_handshake_timeout=ssl_handshake_timeout,
             call_connection_made=False)
 
+        # Pause early so that "ssl_protocol.data_received()" doesn't
+        # have a chance to get called before "ssl_protocol.connection_made()".
+        transport.pause_reading()
+
         transport.set_protocol(ssl_protocol)
         self.call_soon(ssl_protocol.connection_made, transport)
-        if not transport.is_reading():
-            self.call_soon(transport.resume_reading)
+        self.call_soon(transport.resume_reading)
 
         await waiter
         return ssl_protocol._app_transport

diff --git a/Misc/NEWS.d/next/Library/2018-05-29-00-37-56.bpo-33674.2IkGhL.rst b/Misc/NEWS.d/next/Library/2018-05-29-00-37-56.bpo-33674.2IkGhL.rst
@@ -0,0 +1,2 @@
+Pause the transport as early as possible to further reduce the risk of
+data_received() being called before connection_made().