Interface ConsumerPartitionAssignor
- All Known Implementing Classes:
org.apache.kafka.clients.consumer.internals.AbstractPartitionAssignor
,org.apache.kafka.clients.consumer.internals.AbstractStickyAssignor
,CooperativeStickyAssignor
,RangeAssignor
,RoundRobinAssignor
,StickyAssignor
public interface ConsumerPartitionAssignor
This interface is used to define custom partition assignment for use in
KafkaConsumer
. Members of the consumer group subscribe
to the topics they are interested in and forward their subscriptions to a Kafka broker serving
as the group coordinator. The coordinator selects one member to perform the group assignment and
propagates the subscriptions of all members to it. Then assign(Cluster, GroupSubscription)
is called
to perform the assignment and the results are forwarded back to each respective members
In some cases, it is useful to forward additional metadata to the assignor in order to make
assignment decisions. For this, you can override subscriptionUserData(Set)
and provide custom
userData in the returned Subscription. For example, to have a rack-aware assignor, an implementation
can use this user data to forward the rackId belonging to each member.-
Nested Class Summary
Modifier and TypeInterfaceDescriptionstatic final class
static final class
static final class
static enum
The rebalance protocol defines partition assignment and revocation semantics.static final class
-
Method Summary
Modifier and TypeMethodDescriptionassign
(Cluster metadata, ConsumerPartitionAssignor.GroupSubscription groupSubscription) Perform the group assignment given the member subscriptions and current cluster metadata.static List<ConsumerPartitionAssignor>
Get a list of configured instances ofConsumerPartitionAssignor
based on the class names/types specified byConsumerConfig.PARTITION_ASSIGNMENT_STRATEGY_CONFIG
name()
Unique name for this assignor (e.g.default void
onAssignment
(ConsumerPartitionAssignor.Assignment assignment, ConsumerGroupMetadata metadata) Callback which is invoked when a group member receives its assignment from the leader.default ByteBuffer
subscriptionUserData
(Set<String> topics) Return serialized data that will be included in theConsumerPartitionAssignor.Subscription
sent to the leader and can be leveraged inassign(Cluster, GroupSubscription)
((e.g.Indicate which rebalance protocol this assignor works with; By default it should always work withConsumerPartitionAssignor.RebalanceProtocol.EAGER
.default short
version()
Return the version of the assignor which indicates how the user metadata encodings and the assignment algorithm gets evolved.
-
Method Details
-
subscriptionUserData
Return serialized data that will be included in theConsumerPartitionAssignor.Subscription
sent to the leader and can be leveraged inassign(Cluster, GroupSubscription)
((e.g. local host/rack information)- Parameters:
topics
- Topics subscribed to throughKafkaConsumer.subscribe(java.util.Collection)
and variants- Returns:
- nullable subscription user data
-
assign
ConsumerPartitionAssignor.GroupAssignment assign(Cluster metadata, ConsumerPartitionAssignor.GroupSubscription groupSubscription) Perform the group assignment given the member subscriptions and current cluster metadata.- Parameters:
metadata
- Current topic/broker metadata known by consumergroupSubscription
- Subscriptions from all members including metadata provided throughsubscriptionUserData(Set)
- Returns:
- A map from the members to their respective assignments. This should have one entry for each member in the input subscription map.
-
onAssignment
default void onAssignment(ConsumerPartitionAssignor.Assignment assignment, ConsumerGroupMetadata metadata) Callback which is invoked when a group member receives its assignment from the leader.- Parameters:
assignment
- The local member's assignment as provided by the leader inassign(Cluster, GroupSubscription)
metadata
- Additional metadata on the consumer (optional)
-
supportedProtocols
Indicate which rebalance protocol this assignor works with; By default it should always work withConsumerPartitionAssignor.RebalanceProtocol.EAGER
. -
version
default short version()Return the version of the assignor which indicates how the user metadata encodings and the assignment algorithm gets evolved. -
name
String name()Unique name for this assignor (e.g. "range" or "roundrobin" or "sticky"). Note, this is not required to be the same as the class name specified inConsumerConfig.PARTITION_ASSIGNMENT_STRATEGY_CONFIG
- Returns:
- non-null unique name
-
getAssignorInstances
static List<ConsumerPartitionAssignor> getAssignorInstances(List<String> assignorClasses, Map<String, Object> configs) Get a list of configured instances ofConsumerPartitionAssignor
based on the class names/types specified byConsumerConfig.PARTITION_ASSIGNMENT_STRATEGY_CONFIG
-