ApsaraMQ for RabbitMQ:Configuring automatic connection recovery for clients

Recovery triggers

Automatic recovery triggers when:

• An I/O exception is thrown.

• A socket read operation times out.

• Server heartbeats are missed.

Configure recovery in Java

The following methods control connection and topology recovery (queues, exchanges, bindings, and consumers).

ConnectionFactory factory = new ConnectionFactory();
// The endpoint. You can obtain the endpoint of an instance on the Instance Details page in the ApsaraMQ for RabbitMQ console.
factory.setHost("xxx.xxx.aliyuncs.com");
// Replace ${instanceId} with the ID of the ApsaraMQ for RabbitMQ instance. You can obtain the instance ID on the Instances page in the ApsaraMQ for RabbitMQ console.
factory.setCredentialsProvider(new AliyunCredentialsProvider("${instanceId}"));
// The virtual host name. Make sure that the virtual host is created in the ApsaraMQ for RabbitMQ console.
factory.setVirtualHost("${VhostName}");
// The default port. Use port 5672 for non-encrypted connections and port 5671 for encrypted connections.
factory.setPort(5672);
// The timeout period. Set the value based on the network environment.
factory.setConnectionTimeout(30 * 1000);
factory.setHandshakeTimeout(30 * 1000);
factory.setShutdownTimeout(0);
// Specify whether to enable automatic connection recovery.
factory.setAutomaticRecoveryEnabled(true);
// The retry interval. Set the value to 10 seconds.
factory.setNetworkRecoveryInterval(10000);
// Specify whether to enable automatic topology recovery.
factory.setTopologyRecoveryEnabled(true);
Connection connection = factory.newConnection();

// Initialize a ConnectionFactory object to connect to the RabbitMQ client.
CachingConnectionFactory connectionFactory = new CachingConnectionFactory();
connectionFactory.setHost(host);
connectionFactory.setPort(port);
connectionFactory.setUsername(username);
connectionFactory.setPassword(password);
// The virtual host. You can create a virtual host in the ApsaraMQ for RabbitMQ console or specify the following parameter to automatically create one.
connectionFactory.setVirtualHost(virtualHost);
// Make sure that automatic reconnection is enabled. This way, the client can reconnect to the broker during broker restart.
connectionFactory.getRabbitConnectionFactory().setAutomaticRecoveryEnabled(true);
connectionFactory.getRabbitConnectionFactory().setNetworkRecoveryInterval(10000);
connectionFactory.getRabbitConnectionFactory().setTopologyRecoveryEnabled(true);
// The cache mode. Set this parameter to CONNECTION.
connectionFactory.setCacheMode(CachingConnectionFactory.CacheMode.CONNECTION);
// The maximum number of connections that can be cached in CONNECTION mode.
connectionFactory.setConnectionCacheSize(10);
// The maximum number of channels that can be cached in the CONNECTION mode.
connectionFactory.setChannelCacheSize(64);

return connectionFactory;

Configure recovery in Python

Pika, the Python client library recommended by RabbitMQ, does not support automatic recovery through parameters. Implement reconnection logic with callback functions instead.

Consumer client with Pika-based automatic recovery:

# -*- coding: utf-8 -*-

import logging
import time
import pika

LOG_FORMAT = ('%(levelname) -10s %(asctime)s %(name) -30s %(funcName) '
              '-35s %(lineno) -5d: %(message)s')
LOGGER = logging.getLogger(__name__)
logging.basicConfig(level=logging.INFO, format=LOG_FORMAT)

class Consumer(object):

    def __init__(self, amqp_url, queue):
        self.should_reconnect = False

        self._connection = None
        self._channel = None
        self._closing = False
        self._url = amqp_url

        self._queue = queue

    def connect(self):
        '''
        Create a connection and configure the following callbacks:
        on_open_callback: the callback that is invoked when a connection is created.
        on_open_error_callback: the callback that is invoked when a connection fails to be created.
        on_close_callback: the callback that is invoked when a connection is closed.
        '''
        return pika.SelectConnection(
            parameters=pika.URLParameters(self._url),
            on_open_callback=self.on_connection_open,
            on_open_error_callback=self.on_connection_open_error,
            on_close_callback=self.on_connection_closed)

    def on_connection_open(self, _unused_connection):
        '''
        The callback that is invoked when a connection is created.
        Create a channel and configure the following callback:
        on_channel_open: the callback that is invoked when a channel is created.
        '''
        self._connection.channel(on_open_callback=self.on_channel_open)

    def on_connection_open_error(self, _unused_connection, err):
        """
        The callback that is invoked when a connection fails to be created.
        Print the error message and recreate a connection.
        """
        LOGGER.error('Connection open failed: %s', err)
        self.reconnect()

    def on_connection_closed(self, _unused_connection, reason):
        """
        The callback that is invoked when a connection is closed.
        The following scenarios may occur:
        1. The connection is closed as expected and the client exits.
        2. The client is unexpectedly disconnected and tries to recreate a connection.
        """
        self._channel = None
        if self._closing:
            self._connection.ioloop.stop()
        else:
            LOGGER.warning('Connection closed, reconnect necessary: %s', reason)
            self.reconnect()

    def close_connection(self):
        """
        Close the connection.
        """
        if self._connection.is_closing or self._connection.is_closed:
            LOGGER.info('Connection is closing or already closed')
        else:
            LOGGER.info('Closing connection')
            self._connection.close()

    def reconnect(self):
        """
        Set the self.should_reconnect parameter to True and stop the I/O loop.
        """
        self.should_reconnect = True
        self.stop()

    def on_channel_open(self, channel):
        """
        The callback that is invoked when a channel is created.
        Configure the callback.
        on_channel_closed: the callback that is invoked when a channel is closed.
        Start message consumption from the queue.
        """
        self._channel = channel
        self._channel.add_on_close_callback(self.on_channel_closed)
        self.start_consuming()

    def on_channel_closed(self, channel, reason):
        """
        The callback that is invoked when a channel is closed.
        Print channel information and close the connection
        """
        LOGGER.warning('Channel %i was closed: %s', channel, reason)
        self.close_connection()

    def start_consuming(self):
        """
        Start message consumption from the queue.
        """
        LOGGER.info('start consuming...')
        self._channel.basic_consume(
            self._queue, self.on_message)

    def on_message(self, _unused_channel, basic_deliver, properties, body):
        """
        Consume messages and upload acknowledgment (ACK).
        """
        LOGGER.info('Received message: %s', body.decode())
        # The consumption logic.
        self._channel.basic_ack(basic_deliver.delivery_tag)

    def run(self):
        """
        Create a connection and start the I/O loop.
        """
        self._connection = self.connect()
        self._connection.ioloop.start()

    def stop(self):
        """
        Stop the I/O loop.
        """
        if not self._closing:
            self._closing = True
            self._connection.ioloop.stop()
            LOGGER.info('Stopped')


class AutoRecoveryConsumer(object):

    def __init__(self, amqp_url, queue):
        self._amqp_url = amqp_url
        self._queue = queue
        self._consumer = Consumer(self._amqp_url, queue)

    def run(self):
        """
        Perform the while True loop until the KeyboardInterrupt exception is thrown.
        In the run() method, the queue to which the I/O loop listens is started and messages are processed. The loop ensures that the consumer can continuously run and automatically reconnect to the broker.
        """
        while True:
            try:
                self._consumer.run()
            except KeyboardInterrupt:
                self._consumer.stop()
                break
            self._maybe_reconnect()

    def _maybe_reconnect(self):
        """
        Determine whether a reconnection is required. The interval between two consecutive reconnections is 1 second.
        """
        if self._consumer.should_reconnect:
            self._consumer.stop()
            time.sleep(1)
            self._consumer = Consumer(self._amqp_url, self._queue)


def main():
    username = 'MjoxODgwNzcwODY5MD****'
    password = 'NDAxREVDQzI2MjA0OT****'
    host = '1880770****.mq-amqp.cn-hangzhou-a.aliyuncs.com'
    port = 5672
    vhost = 'vhost_test'

    # amqp_url: amqp://<username>:<password>@<host>:<port>/<vhost>
    amqp_url = 'amqp://%s:%s@%s:%i/%s' % (username, password, host, port, vhost)
    consumer = AutoRecoveryConsumer(amqp_url, 'QueueTest')
    consumer.run()


if __name__ == '__main__':
    main()

Configure recovery in PHP

php-amqplib is a PHP library for AMQP-compatible message queues. php-amqplib does not support automatic recovery through parameters. Implement reconnection logic manually.

Consumer client with php-amqplib-based automatic recovery:

<?php

require_once __DIR__ . '/vendor/autoload.php';

use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Exception\AMQPRuntimeException;
use PhpAmqpLib\Exception\AMQPConnectionClosedException;

const ONE_SECOND = 1;


/**
 * Create a connection.
 */
function connect() {
    $host = '1880770****.mq-amqp.cn-hangzhou-a.aliyuncs.com';
    $username = 'NDAxREVDQzI2MjA0OT****';
    $password = 'NDAxREVDQzI2MjA0OT****';
    $port = 5672;
    $vhost = 'vhost_test';
    return new AMQPStreamConnection($host, $port, $username, $password, $vhost);
}

/**
 * Release a connection.
 */
function cleanup_connection($connection) {
    try {
        if($connection !== null) {
            $connection->close();
        }
    } catch (\ErrorException $e) {
    }
}

$connection = null;

while(true){
    try {
        $connection = connect();
        start_consuming($connection);
    } catch (AMQPConnectionClosedException $e) {
        echo $e->getMessage() . PHP_EOL;
        cleanup_connection($connection);
        sleep(ONE_SECOND);
    } catch(AMQPRuntimeException $e) {
        echo $e->getMessage() . PHP_EOL;
        cleanup_connection($connection);
        sleep(ONE_SECOND);
    } catch(\RuntimeException $e) {
        echo 'Runtime exception ' . PHP_EOL;
        cleanup_connection($connection);
        sleep(ONE_SECOND);
    } catch(\ErrorException $e) {
        echo 'Error exception ' . PHP_EOL;
        cleanup_connection($connection);
        sleep(ONE_SECOND);
    }
}

/**
 * Start consumption.
 * @param AMQPStreamConnection $connection
 */
function start_consuming($connection) {
    $queue = 'queueTest';
    $consumerTag = 'consumer';
    $channel = $connection->channel();
    $channel->queue_declare($queue, false, true, false, false);
    $channel->basic_consume($queue, $consumerTag, false, false, false, false, 'process_message');
    while ($channel->is_consuming()) {
        $channel->wait();
    }
}


/**
 * Process the message.
 * @param \PhpAmqpLib\Message\AMQPMessage $message
 */
function process_message($message)
{
    // Process the business logic.
    echo "\n--------\n";
    echo $message->body;
    echo "\n--------\n";

    $message->ack();
}

Limitations

• Connection failure detection takes time. Use Publisher Confirms to prevent message loss during detection.

• Channel exceptions do not trigger automatic recovery. Handle these application-level errors in your code.

• Connection recovery does not restore channels.

• When a connection drops, its exclusive queues are deleted and their data is cleared. Consuming from those queues fails after recovery.

• Each consumer on a connection must have a unique consumer tag. If consumers share a tag, only one is recovered. Omit the tag to let the broker assign one automatically.