使用 RabbitMQ 的 pika 确认消息

Question

I'm using RabbitMQ for message exchange between different docker containers. On the client side I use pika for communication with RabbitMQ. Now the following problem appeared:

Using BlockingConnection I receive a message in my consumer which triggers a quite time consuming task. During processing of this task RabbitMQ closed the connection because the heartbeat wasn't sent from the consuming connection as it's busy processing the task.

The solution I came up to deal with this is that I shutoff the automatic acknowledgment in pika when attaching a callback to the consumer queue like this channel.basic_consume(queue='myqueue', on_message_callback=my_callback, auto_ack=False) . Additionally I moved the time consuming processing to a daemonized python thread in order to allow the BlockingConnection to send the heartbeat required by RabbitMQ.

Now I need to acknowledge the RabbitMQ message from the thread once the processing is finished. For that I extract the delivery_tag from the method as well as the channel_number from the channel property provided by pika.

channel_number = channel.channel_number
delivery_tag = method.delivery_tag

Now in the thread I create a new connection as pika is not threadsafe

conn = BlockingConnection(ConnectionParameters(host="rabbitmq"))
channel = conn.channel(channel_number=channel_number)
channel.queue_declare(queue='myqueue', durable=False)
channel.basic_ack(delivery_tag=delivery_tag)
conn.close()

to acknowledge the message.

However the acknowleging doesn't work as pika yields this warnings:

WARNING:pika.channel:Received remote Channel.Close (406): 'PRECONDITION_FAILED - unknown delivery tag 1' on <Channel number=1 CLOSING conn=<SelectConnection OPEN transport=<pika.adapters.utils.io_services_utils._AsyncPlaintextTransport object at 0x7f94f1dad9e8> params=<ConnectionParameters host=rabbitmq port=5672 virtual_host=/ ssl=False>>>
WARNING:pika.adapters.blocking_connection:Got ChannelClosed while closing channel from connection.close: ChannelClosedByBroker: (406) 'PRECONDITION_FAILED - unknown delivery tag 1'

Q1: Is it possible to acknowledge a message from connection B which was received by connection A?

Q2: Any idea why this is not working?

I read about rabbitpy and AMQPStorm and try those now

Answer 1

使用此示例后的add_callback_threadsafe函数解决了该add_callback_threadsafe 。