AMQP 模型:connection、channel、exchange、queue、binding

  C→S  ch0  ProtocolHeader            8 字节
  S→C  ch0  Connection.Start        528 字节
  C→S  ch0  Connection.StartOk      328 字节
  S→C  ch0  Connection.Tune          20 字节
  C→S  ch0  Connection.TuneOk        20 字节
  C→S  ch0  Connection.Open          16 字节
  S→C  ch0  Connection.OpenOk        13 字节
  握手共 7 帧,客户端发 4 帧、broker 发 3 帧;连接上协商出来的 heartbeat = 60 秒,frame_max = 131072
  broker 在 Connection.Start 里告知的产品和版本: RabbitMQ 4.3.6;它支持的能力(capabilities)里,值为 True 的有: ['authentication_failure_close', 'basic.nack', 'connection.blocked', 'consumer_cancel_notify', 'consumer_priorities', 'direct_reply_to', 'exchange_exchange_bindings', 'per_consumer_qos', 'publisher_confirms']

  C→S  ch1  Exchange.Declare         33 字节
  S→C  ch1  Exchange.DeclareOk       12 字节
  C→S  ch1  Queue.Declare            26 字节
  S→C  ch1  Queue.DeclareOk          27 字节
  C→S  ch1  Queue.Bind               36 字节
  S→C  ch1  Queue.BindOk             12 字节
  C→S  ch1  Basic.Publish            25 字节
  C→S  ch1  ContentHeader            22 字节
  C→S  ch1  ContentBody              13 字节
  C→S  ch1  Basic.Get                22 字节
  S→C  ch1  Basic.GetOk              35 字节
  S→C  ch1  ContentHeader            22 字节
  S→C  ch1  ContentBody              13 字节
  C→S  ch1  Basic.Ack                21 字节
  发布 5 个字节的消息 b"hello" 用了三个帧:Basic.Publish(方法帧)+ ContentHeader(属性与消息总长度)+ ContentBody(消息体);收到的 body = b'hello'

  $ rabbitmqctl list_connections name state channels peer_port
    Listing connections ...
    name	state	channels	peer_port
    127.0.0.1:58737 -> 127.0.0.1:9504	running	3	58737
  $ rabbitmqctl list_channels number consumer_count messages_unacknowledged
    Listing channels ...
    number	consumer_count	messages_unacknowledged
    1	0	0
    2	0	0
    3	0	0
  pika 里三个 channel 的编号: [1, 2, 3]

  对不存在的队列做 passive declare → ChannelClosedByBroker: (404, "NOT_FOUND - no queue 'q.nonexistent' in vhost '/'")
  channel 1 状态: is_open=True;出错的 channel: is_open=False;连接: is_open=True
  $ rabbitmqctl list_channels number consumer_count
    Listing channels ...
    number	consumer_count
    1	0
    3	0
  对没发过的 delivery_tag 做 ack → channel 被关: ["(406, 'PRECONDITION_FAILED - unknown delivery tag 999999')"]
  线上帧: [('C→S', 3, 'Basic.Ack', 21), ('S→C', 3, 'Channel.Close', 68), ('C→S', 3, 'Channel.CloseOk', 12)]
  之后:出错的 channel is_open=False;连接 is_open=True
  声明一个不存在的 exchange 类型 → ChannelClosedByBroker: (406, "PRECONDITION_FAILED - unknown exchange type 'nosuchtype'")
  (broker 发的是 Channel.Close,reply-code 406;只关出错的 channel,连接 c2.is_open=True)
  连一个不存在的 vhost → ProbableAccessDeniedError: ConnectionClosedByBroker: (530) 'NOT_ALLOWED - vhost nope not found'
  用错误的密码 → ProbableAuthenticationError: ConnectionClosedByBroker: (403) 'ACCESS_REFUSED - Login was refused using authentication mechanism PLAIN. For 
  这两种是连接级错误:broker 发 Connection.Close(或直接断开),整条 TCP 连接都没了,上面所有 channel 一起作废

  $ rabbitmqctl list_exchanges name type durable auto_delete
    Listing exchanges for vhost / ...
    name	type	durable	auto_delete
    	direct	true	false
    amq.direct	direct	true	false
    amq.fanout	fanout	true	false
    amq.headers	headers	true	false
    amq.match	headers	true	false
    amq.rabbitmq.log	topic	true	false
    amq.rabbitmq.trace	topic	true	false
    amq.topic	topic	true	false
    x.demo	direct	true	false
  $ rabbitmqctl list_queues name durable messages
    Timeout: 60.0 seconds ...
    Listing queues for vhost / ...
    name	durable	messages
    q.demo	true	0
  $ rabbitmqctl list_bindings source_name source_kind destination_name destination_kind routing_key
    Listing bindings for vhost /...
    source_name	source_kind	destination_name	destination_kind	routing_key
    	exchange	q.demo	queue	q.demo
    x.demo	exchange	q.demo	queue	k1

  基线: Erlang 进程 385,内存 62.8 MiB
  100 个连接 × 1 个 channel: 进程 1485(+1100),内存 70.0 MiB(+7.2)
  关掉后回到: 进程 385,内存 64.5 MiB
  1 个连接 × 100 个 channel: 进程 792(+407),内存 66.7 MiB(+2.3)