Runtime parameters

RabbitMQ provides environment variables and configuration variables to configure RabbitMQ when starting the RabbitMQ server. In addition to these configurations, RabbitMQ allows us to change parameters, which were set in the environment variables and configuration variables in the runtime using the runtime parameters.

We can use the command-line tool for managing the RabbitMQ broker for changing the runtime parameters, as shown in the following screenshot:

Runtime parameters

Image 2: Command Line Tool for Managing a RabbitMQ broker

Parameter management

Parameter management is a way to configure RabbitMQ by setting the parameter values. We are able to change parameters using the set_parameter command of rabbitmqctl. Moreover, we can change the different types of components of RabbitMQ with the given component_name attribute. The following tables shows the parameters and description of the runtime parameters:

Parameter

Description

set_parameter [-p vhostpath] {component_name} {name} {value}

The set_parameter parameter performs the setting of the parameters of a given component at runtime.

clear_parameter [-p vhostpath] {component_name} {key}

The clear_parameter parameter removes all of the parameters of a given component at runtime.

Policy management

Policy management is configuration of the RabbitMQ policy values. RabbitMQ gives us an opportunity to change its policies for message queues in the runtime, and its policies are applicable for exchange and queues. You can set the new policies using "set_policy", whereas you can clear all the policies using "clear_policy".

Parameter

Description

set_policy [-p vhostpath] [--priority priority] [--apply-to apply-to] {name} {pattern} {definition}

The set_policy parameter performs a change of the behavior of the queues and exchanges by setting the given pattern and definition.

clear_policy [-p vhostpath] {name}

The clear_policy parameter removes all of the policies, which is given with the name parameter.

Memory management

Memory management is the configuration of RabbitMQ memory values. Memory management can be done through the RabbitMQ configuration file parameters as we saw in the previous sections. But, sometimes we have to change the memory threshold to a lower value for many client attractions. RabbitMQ gives an option to the change memory threshold using the "set_vm_memory_high_watermark" runtime parameter as shown in the following table:

Parameter

Description

set_vm_memory_high_watermark {fraction}

The set_vm_memory_high_watermark parameter changes the memory threshold fraction.

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