Merge pull request #23945 from lidizheng/aio-ref-count-fix

[Aio] Prevent call objects from outliving its parent channel or server

src/python/grpcio/grpc/_cython/_cygrpc/aio/call.pyx.pxi

@@ -46,6 +46,7 @@ cdef class _AioCall(GrpcCallWrapper):
 
     def __cinit__(self, AioChannel channel, object deadline,
                   bytes method, CallCredentials call_credentials, object wait_for_ready):
+        init_grpc_aio()
         self.call = NULL
         self._channel = channel
         self._loop = channel.loop
@@ -63,6 +64,7 @@ cdef class _AioCall(GrpcCallWrapper):
     def __dealloc__(self):
         if self.call:
             grpc_call_unref(self.call)
+        shutdown_grpc_aio()
 
     def _repr(self) -> str:
         """Assembles the RPC representation string."""

src/python/grpcio/grpc/_cython/_cygrpc/aio/server.pyx.pxi

@@ -45,6 +45,7 @@ class _ServerStoppedError(BaseError):
 cdef class RPCState:
 
     def __cinit__(self, AioServer server):
+        init_grpc_aio()
         self.call = NULL
         self.server = server
         grpc_metadata_array_init(&self.request_metadata)
@@ -106,6 +107,7 @@ cdef class RPCState:
         grpc_metadata_array_destroy(&self.request_metadata)
         if self.call:
             grpc_call_unref(self.call)
+        shutdown_grpc_aio()
 
 
 cdef class _ServicerContext: