Start message queue consumers

In addition to the command arguments described in this topic, see Common arguments.

Run all Magento CLI commands as the Magento file system owner.

You must start a message queue consumer to enable asynchronous operations such as Inventory Management mass actions and REST bulk and asynchronous endpoints. To enable B2B functionality, you must start multiple consumers. Third-party modules might also require that you start a custom consumer.

View a list of available message queue consumers

To view a list of all consumers:

bin/magento queue:consumers:list

To start message queue consumers:

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.

Parameter	Value	Required?	Default Value
`--max-messages=<value>`	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 `--max-messages`, the process runs continuously.	No	0
`--consumers-wait-for-messages=<value>`	Specifies whether consumers should continue polling for messages if the number of processed messages is less than the `max-messages` value. The default value of `0` prevents stuck deployments caused by long delays in message queue processing. Set the value to `1` to allow consumers to wait for messages. On Magento Commerce Cloud projects, this variable is set by default using the `CONSUMERS_WAIT_FOR_MAX_MESSAGES` deploy variable.	No	0
`--batch-size=<value>`	The number of messages to consume per batch. If specified, messages in a queue are consumed in batches of `<value>` each. This option is applicable for the batch consumer only. If `--batch-size` is not defined, the batch consumer receives all available messages in a queue.	No	0
`--pid-file-path=<value>`	This option is deprecated. Use the `single-thread` option instead.	No
`--single-thread`	This option prevents running multiple copies of a consumer simultaneously.	No
`--area-code=<value>`	The area code preferred for consumer process.	No	global
`<consumer_name>`	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:

bin/magento queue:consumers:start <consumer_name> &