Improve close behavior

msrest/service_client.py

@@ -284,8 +284,15 @@ def send(self, request, headers=None, content=None, **config):
             msg = "Error occurred in request."
             raise_with_traceback(ClientRequestError, msg, err)
         finally:
-            if not response or not kwargs['stream']:
-                session.close()
+            self._close_local_session_if_necessary(response, session, kwargs['stream'])
+
+    def _close_local_session_if_necessary(self, response, session, stream):
+        # Do NOT close session if session is self._session. No exception.
+        if self._session is session:
+            return
+        # Here, it's a local session, I might close it.
+        if not response or not stream:
+            session.close()
 
     def stream_download(self, data, callback):
         """Generator for streaming request body data.

tests/test_client.py

@@ -132,9 +132,11 @@ def signed_session(self, session=None):
                 client.send(req)  # Will fail, I don't care, that's not the point of the test
             except Exception:
                 pass
+            assert client._session  # Still alive
 
         assert not cfg.keep_alive
         assert creds.called == 2
+        assert client._session is None  # Dead
 
     def test_keep_alive(self):
 
@@ -168,6 +170,10 @@ def signed_session(self, session=None):
             pass
 
         assert creds.called == 2
+        assert client._session  # Still alive
+        # Manually close the client in "keep_alive" mode
+        client.close()
+        assert client._session is None  # Dead
 
     def test_max_retries_on_default_adapter(self):
         # max_retries must be applied only on the default adapters of requests