Migration

Pulsar has 3 types of broker load balancers, that is, simple, modular, and extensible.

You can perform the following migrations.

Migration	When to use
Migrate from simple to modular	If you want to use the bundle unloading strategy of OverloadShedder, ThresholdShedder, or UniformLoadShedder.
Migrate from modular to extensible	If you want to use the bundle unloading strategy of TransferShedder.
Migrate from extensible to modular	If you want to use the bundle unloading strategy of OverloadShedder, ThresholdShedder, or UniformLoadShedder.

note

It is not recommended to migrate from the modular or extensible to the simple broker load balancer since the simple broker load balancer is deprecated and no longer in use.

Considerations

Before migrating from one broker load balancer type to another, review the relationship between broker load balancer type, Pulsar version, and bundle unloading strategy. You may need to upgrade Pulsar versions or update the bundle unloading strategy. Below are brief summaries.

This broker load balancer type	is available in this Pulsar version
Simple	All versions
Modular	1.7 and later
Extensible	3.0 and later

This bundle unloading strategy	is available for this broker load balancer type	in available this Pulsar version
OverloadShedder	Modular	1.18 and later
ThresholdShedder	Modular	2.6 and later
UniformLoadShedder	Modular	2.10 and later
TransferShedder	Extensible	3.0 and later

Migrate from simple to modular broker load balancer

You can migrate from the simple to the modular broker load balancer, by manually changing the configuration settings in the broker.conf file or by using the pulsar-admin tool.

Change broker.conf file

1. Access to the broker.conf file.

   vim apache-pulsar-4.0.0/conf/broker.conf

2. Change the broker load balancer by setting loadManagerClassName to ModularLoadManagerImpl in the broker.conf file.

   loadManagerClassName=org.apache.pulsar.broker.loadbalance.extensions.ModularLoadManagerImpl

3. Restart the Pulsar cluster. The new setting will take effect after the restart.

Use pulsar-admin tool

1. Access the pulsar-admin tool.

   cd apache-pulsar-4.0.0/bin

2. Set --config to loadManagerClassName and --value to org.apache.pulsar.broker.loadbalance.impl.ModularLoadManagerImpl.

   pulsar-admin brokers update-dynamic-config \
   --config loadManagerClassName \
   --value org.apache.pulsar.broker.loadbalance.impl.ModularLoadManagerImpl

   You do not need to restart the Pulsar cluster. The new settings will take effect after 1 to 2 minutes.

Migrate from modular to extensible broker load balancer

You can migrate from the modular to the extensible broker load balancer, by manually changing settings in the broker.conf file. During the migration, the lookup and assignment will be redirected to the brokers with the extensible load balancer.

note

The pulsar-admin tool is not supported for this migration.

Change broker.conf file

1. Upgrade the Pulsar cluster to 3.0.0 or later versions.

2. Access to the broker.conf file.

   vim apache-pulsar-4.0.0/conf/broker.conf

3. Change the following settings in the broker.conf file:

   • Update broker load balancer by setting loadManagerClassName to ExtensibleLoadManagerImpl.

   • Update bundle unloading strategy by setting loadBalancerLoadSheddingStrategy to TransferShedder.

   loadManagerClassName=org.apache.pulsar.broker.loadbalance.extensions.ExtensibleLoadManagerImpl 
   
   loadBalancerLoadSheddingStrategy=org.apache.pulsar.broker.loadbalance.extensions.scheduler.TransferShedder
   note

   • The extensible broker load balancer is available in Pulsar 3.0.0 or later.
   • The TransferShedder unloading strategy is only available in the extensible load balancer.

4. Restart the Pulsar cluster. The new settings will take effect after the restart.

Migrate from extensible to modular broker load balancer

You can migrate from the extensible to the modular broker load balancer, by manually changing the setting in the broker.conf file. During the migration, the lookup and assignment will be redirected to the brokers with the modular load balancer.

note

The pulsar-admin tool is not supported for this migration.

Change broker.conf file

1. Access to the broker.conf file.

   vim apache-pulsar-4.0.0/conf/broker.conf

2. Change the following settings in the broker.conf file:

   • Update broker load balancer by setting loadManagerClassName to ModularLoadManagerImpl

   • Update bundle unloading strategy to OverloadShedder, ThresholdShedder, or UniformLoadShedder based on your needs.

   loadManagerClassName=org.apache.pulsar.broker.loadbalance.impl.ModularLoadManagerImpl
   
   loadBalancerLoadSheddingStrategy=org.apache.pulsar.broker.loadbalance.impl.ThresholdShedder
   note

   TransferShedder is only supported in the extensible broker load balancer, so you need to change TransferShedder to other bundle unloading strategies.

3. Restart the Pulsar cluster. The new settings will take effect after the restart.

Related topics

• To get a comprehensive understanding and discover the key insights, see Broker load balancing | Overview.

• To discover different usage scenarios, see Broker load balancing | Use cases.

• To explore functionalities, see Broker load balancing | Features.

• To understand advantages, see Broker load balancing | Benefits.

• To learn essential fundamentals, see Broker load balancing | Concepts.

• To review various versions of broker load balancers, see Broker load balancing | Types.