stop in python, closable only in scala

Author: ehigham

hail/python/hail/backend/py4j_backend.py

@@ -187,7 +187,7 @@ def decode_bytearray(encoded):
         self._jbackend = jbackend
         self._jhc = jhc
 
-        self._backend_server = self._hail_package.backend.BackendServer.apply(self._jbackend)
+        self._backend_server = self._hail_package.backend.BackendServer(self._jbackend)
         self._backend_server_port: int = self._backend_server.port()
         self._backend_server.start()
         self._requests_session = requests.Session()
@@ -307,6 +307,7 @@ def _to_java_blockmatrix_ir(self, ir):
 
     def stop(self):
         self._backend_server.close()
+        self._jbackend.close()
         self._jhc.stop()
         self._jhc = None
         self._registered_ir_function_names = set()

hail/python/hail/context.py

@@ -151,7 +151,7 @@ def default_reference(self, value):
 
     def stop(self):
         assert self._backend
-        self._backend.close()
+        self._backend.stop()
         self._backend = None
         Env._hc = None
         Env._dummy_table = None