Fix _SelectorDatagramTransport constructor

Only start reading after connection_made() has been called.

1 files changed, 3 insertions, 1 deletions

diff --git a/asyncio/selector_events.py b/asyncio/selector_events.py
index f499629..5fe46e5 100644
--- a/asyncio/selector_events.py
+++ b/asyncio/selector_events.py
@@ -928,8 +928,10 @@ class _SelectorDatagramTransport(_SelectorTransport):
                  waiter=None, extra=None):
         super().__init__(loop, sock, protocol, extra)
         self._address = address
-        self._loop.add_reader(self._sock_fd, self._read_ready)
         self._loop.call_soon(self._protocol.connection_made, self)
+        # only start reading when connection_made() has been called
+        self._loop.call_soon(self._loop.add_reader,
+                             self._sock_fd, self._read_ready)
         if waiter is not None:
             # only wake up the waiter when connection_made() has been called
             self._loop.call_soon(waiter._set_result_unless_cancelled, None)