akka.stream

Class Fusing

java.lang.Object

akka.stream.Fusing

public class Fusing
extends java.lang.Object

This class holds some graph transformation functions that can fuse together multiple operation stages into synchronous execution islands. The purpose is to reduce the number of Actors that are created in order to execute the stream and thereby improve start-up cost as well as reduce element traversal latency for large graphs. Fusing itself is a time-consuming operation, meaning that usually it is best to cache the result of this computation and reuse it instead of fusing the same graph many times.

Fusing together all operations which allow this treatment will reduce the parallelism that is available in the stream graph’s execution—in the worst case it will become single-threaded and not benefit from multiple CPU cores at all. Where parallelism is required, the akka.stream.Attributes#AsyncBoundary attribute can be used to declare subgraph boundaries across which the graph shall not be fused.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Fusing.FusedGraph<S extends Shape,M> A fused graph of the right shape, containing a FusedModule which holds more information on the operation structure of the contained stream topology for convenient graph traversal.
static class	Fusing.FusedGraph$

Constructor Summary

Constructors

Constructor and Description
Fusing()

Method Summary

Modifier and Type	Method and Description
static <S extends Shape,M> Fusing.FusedGraph<S,M>	aggressive(Graph<S,M> g) Fuse all operations where this is technically possible (i.e.
static <S extends Shape,M> StreamLayout.StructuralInfoModule	structuralInfo(Graph<S,M> g, Attributes attributes) Return the StructuralInfo for this Graph without any fusing

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Fusing

public Fusing()

Method Detail

aggressive

public static <S extends Shape,M> Fusing.FusedGraph<S,M> aggressive(Graph<S,M> g)

Fuse all operations where this is technically possible (i.e. all implementations based on GraphStage) and not forbidden via akka.stream.Attributes#AsyncBoundary.

Parameters:

g - (undocumented)

Returns:

(undocumented)

structuralInfo

public static <S extends Shape,M> StreamLayout.StructuralInfoModule structuralInfo(Graph<S,M> g,
                                                                                   Attributes attributes)

Return the StructuralInfo for this Graph without any fusing

Parameters:

g - (undocumented)

attributes - (undocumented)

Returns:

(undocumented)