Fix stdin ZMQ channel

ipykernel/kernelapp.py

@@ -134,6 +134,7 @@ class IPKernelApp(BaseIPythonApplication, InteractiveShellApp, ConnectionFileMix
     heartbeat = Instance(Heartbeat, allow_none=True)
 
     context = Any()
+    sync_context = Any()
     shell_socket = Any()
     control_socket = Any()
     debugpy_socket = Any()
@@ -304,14 +305,15 @@ def init_sockets(self):
         self.log.info("Starting the kernel at pid: %i", os.getpid())
         assert self.context is None, "init_sockets cannot be called twice!"
         self.context = context = zmq.asyncio.Context()
+        self.sync_context = sync_context = zmq.Context()
         atexit.register(self.close)
 
         self.shell_socket = context.socket(zmq.ROUTER)
         self.shell_socket.linger = 1000
         self.shell_port = self._bind_socket(self.shell_socket, self.shell_port)
         self.log.debug("shell ROUTER Channel on port: %i" % self.shell_port)
 
-        self.stdin_socket = context.socket(zmq.ROUTER)
+        self.stdin_socket = sync_context.socket(zmq.ROUTER)
         self.stdin_socket.linger = 1000
         self.stdin_port = self._bind_socket(self.stdin_socket, self.stdin_port)
         self.log.debug("stdin ROUTER Channel on port: %i" % self.stdin_port)
@@ -397,6 +399,7 @@ def close(self):
         self.log.debug("Terminating zmq context")
         # FIXME: this line breaks shutdown
         # self.context.term()
+        self.sync_context.term()
         self.log.debug("Terminated zmq context")
 
     def log_connection_info(self):