service: unregister receiver at shutdown; closes #445.

docs/changelog.rst

@@ -298,6 +298,12 @@ Core Library
 * `#444 <https://github.com/dw/mitogen/issues/444>`_: messages regarding
   unforwardable extension module are no longer logged as errors.
 
+* `#445 <https://github.com/dw/mitogen/issues/445>`_: service pools unregister
+  the :data:`mitogen.core.CALL_SERVICE` handle at shutdown, ensuring any
+  outstanding messages are either processed by the pool as it shuts down, or
+  have dead messages sent in reply to them, preventing peer contexts from
+  hanging due to a forgotten buffered message.
+
 * `#453 <https://github.com/dw/mitogen/issues/453>`_: the loggers used in
   children for standard IO redirection have propagation disabled, preventing
   accidental reconfiguration of the :mod:`logging` package in a child from

mitogen/service.py

@@ -479,6 +479,7 @@ class Pool(object):
 
     def stop(self, join=True):
         self.closed = True
+        self._receiver.close()
         self._select.close()
         if join:
             self.join()

tests/service_test.py

@@ -89,5 +89,18 @@ class PermissionTest(testlib.RouterMixin, testlib.TestCase):
         self.assertTrue(msg in exc.args[0])
 
 
+class CloseTest(testlib.RouterMixin, testlib.TestCase):
+    klass = mitogen.service.Pool
+
+    def test_receiver_closed(self):
+        pool = self.klass(router=self.router, services=[])
+        pool.stop()
+        self.assertEquals(None, pool._receiver.handle)
+
+        e = self.assertRaises(mitogen.core.ChannelError,
+            lambda: self.router.myself().call_service(MyService, 'foobar'))
+        self.assertEquals(e.args[0], self.router.invalid_handle_msg)
+
+
 if __name__ == '__main__':
     unittest2.main()