Sudden hang when examples/kombu_server.py and kombu_client.py communicate.

When examples/kombu_server.py and kombu_client.py communicate, the communication suddenly stops:

while true;do python examples/kombu_client.py;echo;sleep 1;done

After a few iterations of the loop, the client no longer prints the output of the sum(1,2) RPC calls.

DEBUG:amqp:Start from server, version: 0.9, properties: {'capabilities': {'publisher_confirms': True, 'exchange_exchange_bindings': True, 'basic.nack': True, 'consumer_cancel_notify': True, 'connection.blocked': True, 'consumer_priorities': True, 'authentication_failure_close': True, 'per_consumer_qos': True, 'direct_reply_to': True}, 'cluster_name': 'rabbit@sf314', 'copyright': 'Copyright (c) 2007-2022 VMware, Inc. or its affiliates.', 'information': 'Licensed under the MPL 2.0. Website: https://rabbitmq.com', 'platform': 'Erlang/OTP 24.2.2', 'product': 'RabbitMQ', 'version': '3.9.13'}, mechanisms: [b'AMQPLAIN', b'PLAIN'], locales: ['en_US']
DEBUG:amqp:using channel_id: 1
DEBUG:amqp:Channel open
1 + 2 = 3

I see in the rabbitmq log that server and client stay connected, but the client does not continue sending requests:

In the kombu_server log, I see that the server sends the response for the sum method, but the client does not have any logger calls about sending requests or receiving responses.

This is with a kombu_client.py which requests one sum(1,2) and sends one tick(). The tick after the sum is not received:

DEBUG:pjrpc.server.request:request received: {"jsonrpc": "2.0", "method": "sum", "id": 1, "params": [1, 2]}
DEBUG:pjrpc.server.response:response sent: {"jsonrpc": "2.0", "id": 1, "result": 3}
DEBUG:pjrpc.server.request:request received: {"jsonrpc": "2.0", "method": "tick"}
received tick
DEBUG:pjrpc.server.request:request received: {"jsonrpc": "2.0", "method": "sum", "id": 1, "params": [1, 2]}
DEBUG:pjrpc.server.response:response sent: {"jsonrpc": "2.0", "id": 1, "result": 3}
DEBUG:amqp.connection.Connection.heartbeat_tick:heartbeat_tick : for connection 658eb70988e8400d9bdfb55a26b12b35
DEBUG:amqp.connection.Connection.heartbeat_tick:heartbeat_tick : for connection 658eb70988e8400d9bdfb55a26b12b35
DEBUG:amqp.connection.Connection.heartbeat_tick:heartbeat_tick : for connection 658eb70988e8400d9bdfb55a26b12b35

The server still receives heartbeats and and answers to other clients.

Just a suggestion / hint for diagnosis: I think logging of requests and responses shoud be added to the kombu client to aid in tracing, and

logging.basicConfig(level=logging.DEBUG)

should be added to server and client: For kombu, the even the debug logging is not too verbose.

dapper91 / pjrpc

Sudden hang when examples/kombu_server.py and kombu_client.py communicate. #66