Package com.google.adk.agents

Class ParallelAgent

java.lang.Object

com.google.adk.workflow.BaseNode

com.google.adk.agents.BaseAgent

com.google.adk.agents.ParallelAgent

All Implemented Interfaces:

Node

public class ParallelAgent
extends BaseAgent

A shell agent that runs its sub-agents in parallel in isolated manner.

This approach is beneficial for scenarios requiring multiple perspectives or attempts on a single task, such as running different algorithms simultaneously or generating multiple responses for review by a subsequent evaluation agent.

Composition with LlmAgents: a ParallelAgent does not transfer control back to a parent LlmAgent. To follow a fan-out with an aggregation step, wrap both in a SequentialAgent (used as the root or transferred-to agent). Each parallel sub-agent publishes via outputKey and the aggregator reads via {key} placeholders in its instruction:

 var contacts =
     LlmAgent.builder()
         .name("contacts")
         .model("gemini-flash-latest")
         .instruction("List contacts.")
         .outputKey("contacts")
         .build();
 var schedule =
     LlmAgent.builder()
         .name("schedule")
         .model("gemini-flash-latest")
         .instruction("List schedule.")
         .outputKey("schedule")
         .build();
 var writer =
     LlmAgent.builder()
         .name("writer")
         .model("gemini-flash-latest")
         .instruction("Write: contacts={contacts}, schedule={schedule}")
         .build();
 var gather =
     ParallelAgent.builder().name("gather").subAgents(contacts, schedule).build();
 var root = SequentialAgent.builder().name("root").subAgents(gather, writer).build();
 

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ParallelAgent.Builder	Builder for ParallelAgent.

Method Summary

Modifier and Type	Method	Description
static ParallelAgent.Builder	builder()
static ParallelAgent	fromConfig(ParallelAgentConfig config, String configAbsPath)	Creates a ParallelAgent from configuration.
protected io.reactivex.rxjava3.core.Flowable<Event>	runAsyncImpl(InvocationContext invocationContext)	Runs sub-agents in parallel and emits their events.
protected io.reactivex.rxjava3.core.Flowable<Event>	runLiveImpl(InvocationContext invocationContext)	Not supported for ParallelAgent.

Methods inherited from class com.google.adk.agents.BaseAgent

afterAgentCallback, beforeAgentCallback, canonicalAfterAgentCallbacks, canonicalBeforeAgentCallbacks, close, findAgent, findSubAgent, fromConfig, parentAgent, parentAgent, rootAgent, runAsync, runLive, runNode, subAgents, toolOrigin

Methods inherited from class com.google.adk.workflow.BaseNode

config, description, inputSchema, name, outputSchema, rerunOnResume, stateSchema, waitForOutput

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.google.adk.workflow.Node

requiresAllPredecessors

Method Details

builder

public static ParallelAgent.Builder builder()

fromConfig

public static ParallelAgent fromConfig(ParallelAgentConfig config,
 String configAbsPath)
                                throws ConfigAgentUtils.ConfigurationException

Creates a ParallelAgent from configuration.

Parameters:

config - the agent configuration

configAbsPath - The absolute path to the agent config file.

Returns:

the configured ParallelAgent

Throws:

ConfigAgentUtils.ConfigurationException - if the configuration is invalid

runAsyncImpl

protected io.reactivex.rxjava3.core.Flowable<Event> runAsyncImpl(InvocationContext invocationContext)

Runs sub-agents in parallel and emits their events.

Sets the branch and merges event streams from all sub-agents.

Specified by:

runAsyncImpl in class BaseAgent

Parameters:

invocationContext - Invocation context.

Returns:

Flowable emitting events from all sub-agents.

runLiveImpl

protected io.reactivex.rxjava3.core.Flowable<Event> runLiveImpl(InvocationContext invocationContext)

Not supported for ParallelAgent.

Specified by:

runLiveImpl in class BaseAgent

Parameters:

invocationContext - Invocation context.

Returns:

Flowable that always throws UnsupportedOperationException.