address comments

src/python/grpcio_tests/tests/fork/_fork_interop_test.py

@@ -139,7 +139,7 @@ class ForkInteropTest(unittest.TestCase):
                 out, err = process.communicate()
         except subprocess.TimeoutExpired:
             process.kill()
-            raise ValueError('Process failed to terminate')
+            raise RuntimeError('Process failed to terminate')
         finally:
             timer.cancel()
         self.assertEqual(

src/python/grpcio_tests/tests/fork/methods.py

@@ -136,7 +136,7 @@ class _ChildProcess(object):
     def finish(self):
         self._process.join(timeout=_CHILD_FINISH_TIMEOUT_S)
         if self._process.is_alive():
-            raise ValueError('Child process did not terminate')
+            raise RuntimeError('Child process did not terminate')
         if self._process.exitcode != 0:
             raise ValueError('Child process failed with exitcode %d' %
                              self._process.exitcode)
@@ -236,6 +236,9 @@ def _close_channel_before_fork(channel, args):
 
 def _connectivity_watch(channel, args):
 
+    parent_states = []
+    parent_channel_ready_event = threading.Event()
+
     def child_target():
 
         child_channel_ready_event = threading.Event()
@@ -244,7 +247,6 @@ def _connectivity_watch(channel, args):
             if state is grpc.ChannelConnectivity.READY:
                 child_channel_ready_event.set()
 
-        child_states = []
         with _channel(args) as child_channel:
             child_stub = test_pb2_grpc.TestServiceStub(child_channel)
             child_channel.subscribe(child_connectivity_callback)
@@ -257,9 +259,6 @@ def _connectivity_watch(channel, args):
                     parent_states)
             child_channel.unsubscribe(child_connectivity_callback)
 
-    parent_states = []
-    parent_channel_ready_event = threading.Event()
-
     def parent_connectivity_callback(state):
         parent_states.append(state)
         if state is grpc.ChannelConnectivity.READY:
@@ -275,11 +274,6 @@ def _connectivity_watch(channel, args):
     channel.unsubscribe(parent_connectivity_callback)
     child_process.finish()
 
-    # Need to unsubscribe or _channel.py in _poll_connectivity triggers a
-    # "Cannot invoke RPC on closed channel!" error.
-    # TODO(ericgribkoff) Fix issue with channel.close() and connectivity polling
-    channel.unsubscribe(parent_connectivity_callback)
-
 
 def _ping_pong_with_child_processes_after_first_response(
         channel, args, child_target, run_after_close=True):