Manage message queues
If you don’t want to implement the RabbitMQ solution, you can manage message queues with cron jobs (or an external process manager) and the command line to ensure that consumers are retrieving messages.
Cron jobs are the default mechanism to restart consumers. Processes started by
cron consume the specified number of messages and then terminate. Re-running
cron restarts the consumer.
The following shows a
crontab configuration for running consumers in our implementation, it is the example for understanding how it works:
1 2 3 4 5 ... <job name="consumers_runner" instance="Magento\MessageQueue\Model\Cron\ConsumersRunner" method="run"> <schedule>* * * * *</schedule> </job> ...
How often you check message queues depends on your business logic and available system resources. In general, you’ll probably want to check for newly created customers and send welcome emails more frequently than a more resource intensive process (e.g., updating your catalog). You should define
cron schedules according to your business needs.
It can be configured in Admin Panel Stores > Settings > Configuration > Advanced > System > Cron configuration options for group: consumers
See Configure and run cron for more information about using
cron with Magento.
You can also use a process manager such as Supervisor to monitor the status of processes. The manager can use the command line to restart the processes as needed.
Behavior by default
- Cron job
- Cron job
consumers_runnerruns all defined consumers
- Each consumer processes 10000 messages and then terminates
Edit /app/etc/env.php file for configure cron job
1 2 3 4 5 6 7 8 9 10 ... 'cron_consumers_runner' => array( 'cron_run' => false, 'max_messages' => 20000, 'consumers' => array( 'consumer1', 'consumer2', ) ), ...
cron_run- A boolean value that enables or disables the
consumers_runnercron job (default =
max_messages- The maximum number of messages each consumer must process before terminating (default =
10000). Although we do not recommend it, you can use 0 to prevent the consumer from terminating.
consumers- An array of strings specifying which consumer(s) to run. An empty array runs all consumers.
View a list of available message queue consumers
To view a list of all consumers:
1 bin/magento queue:consumers:list
Start message queue consumers
To start message queue consumers:
1 bin/magento queue:consumers:start [--max-messages=<value>] [--batch-size=<value>] [--single-thread] [--area-code=<value>] <consumer_name>
The following table explains this command’s options, parameters, and values.
||The maximum number of messages to consume per invocation. If the number of queued messages is less than the specified max, the consumer polls for new messages until it has processed the max. If you don’t specify
||The number of messages to consume per batch. If specified, messages in a queue are consumed in batches of
||This option is deprecated. Use the
||This option prevents running multiple copies of a consumer simultaneously.||No|
||The area code preferred for consumer process.||No||global|
||The consumer to start.||Yes|
After consuming all available messages, the command terminates. You can run the command again manually or with a cron job. You can also run multiple instances of the
magento queue:consumers:start command to process large message queues. For example, you can append
& to the command to run it in the background, return to a prompt, and continue running commands:
1 bin/magento queue:consumers:start <consumer_name> &