Package org.apache.flink.streaming.runtime.partitioner

Class RescalePartitioner<T>

java.lang.Object

org.apache.flink.streaming.runtime.partitioner.StreamPartitioner<T>

org.apache.flink.streaming.runtime.partitioner.RescalePartitioner<T>

Type Parameters:

T - Type of the elements in the Stream being rescaled

All Implemented Interfaces:

Serializable, ChannelSelector<SerializationDelegate<StreamRecord<T>>>

@Internal
public class RescalePartitioner<T>
extends StreamPartitioner<T>

Partitioner that distributes the data equally by cycling through the output channels. This distributes only to a subset of downstream nodes because StreamingJobGraphGenerator instantiates a DistributionPattern.POINTWISE distribution pattern when encountering RescalePartitioner.

The subset of downstream operations to which the upstream operation sends elements depends on the degree of parallelism of both the upstream and downstream operation. For example, if the upstream operation has parallelism 2 and the downstream operation has parallelism 4, then one upstream operation would distribute elements to two downstream operations while the other upstream operation would distribute to the other two downstream operations. If, on the other hand, the downstream operation has parallelism 2 while the upstream operation has parallelism 4 then two upstream operations will distribute to one downstream operation while the other two upstream operations will distribute to the other downstream operations.

In cases where the different parallelisms are not multiples of each other one or several downstream operations will have a differing number of inputs from upstream operations.

See Also:

• Serialized Form

Field Summary

Fields inherited from class org.apache.flink.streaming.runtime.partitioner.StreamPartitioner

numberOfChannels

Constructor Summary

Constructors

Constructor	Description
RescalePartitioner()

Method Summary

Modifier and Type	Method	Description
StreamPartitioner<T>	copy()
SubtaskStateMapper	getDownstreamSubtaskStateMapper()	Defines the behavior of this partitioner, when downstream rescaled during recovery of in-flight data.
SubtaskStateMapper	getUpstreamSubtaskStateMapper()	Defines the behavior of this partitioner, when upstream rescaled during recovery of in-flight data.
boolean	isPointwise()
int	selectChannel(SerializationDelegate<StreamRecord<T>> record)	Returns the logical channel index, to which the given record should be written.
String	toString()

Methods inherited from class org.apache.flink.streaming.runtime.partitioner.StreamPartitioner

disableUnalignedCheckpoints, equals, hashCode, isBroadcast, isSupportsUnalignedCheckpoint, setup

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

RescalePartitioner

public RescalePartitioner()

Method Details

selectChannel

public int selectChannel(SerializationDelegate<StreamRecord<T>> record)

Description copied from interface: ChannelSelector

Returns the logical channel index, to which the given record should be written. It is illegal to call this method for broadcast channel selectors and this method can remain not implemented in that case (for example by throwing UnsupportedOperationException).

Parameters:

record - the record to determine the output channels for.

Returns:

an integer number which indicates the index of the output channel through which the record shall be forwarded.

getDownstreamSubtaskStateMapper

public SubtaskStateMapper getDownstreamSubtaskStateMapper()

Description copied from class: StreamPartitioner

Defines the behavior of this partitioner, when downstream rescaled during recovery of in-flight data.

Specified by:

getDownstreamSubtaskStateMapper in class StreamPartitioner<T>

getUpstreamSubtaskStateMapper

public SubtaskStateMapper getUpstreamSubtaskStateMapper()

Description copied from class: StreamPartitioner

Defines the behavior of this partitioner, when upstream rescaled during recovery of in-flight data.

Overrides:

getUpstreamSubtaskStateMapper in class StreamPartitioner<T>

copy

public StreamPartitioner<T> copy()

Specified by:

copy in class StreamPartitioner<T>

toString

public String toString()

Overrides:

toString in class Object

isPointwise

public boolean isPointwise()

Specified by:

isPointwise in class StreamPartitioner<T>