Implementation:Ray project Ray Ray Task Remote

Knowledge Sources	Ray Ray Tasks
Domains	Distributed_Computing, Task_Scheduling
Last Updated	2026-02-13 17:00 GMT

Overview

Concrete tool for submitting functions as distributed remote tasks provided by the Ray Java SDK.

Description

The Ray.task() static method creates a TaskCaller builder, and calling .remote() on it submits the function for distributed execution. Internally, Ray.task() is defined on RayCall (the superclass of Ray) with overloaded variants for 0 to 6 parameters. TaskCaller.remote() delegates to Ray.internal().call(func, args, options), which resolves the function via FunctionManager, serializes arguments via ArgumentsBuilder.wrap(), and dispatches to NativeTaskSubmitter.submitTask() through JNI.

Usage

Use Ray.task() to submit any stateless function for remote execution on the cluster. Pass the function as a method reference and its arguments as subsequent parameters. Call .remote() to actually submit the task and receive an ObjectRef for the result.

Code Reference

Source Location

• Repository: ray-project/ray
• File: java/api/src/main/java/io/ray/api/RayCall.java (task factory methods, L38-1308)
• File: java/api/src/main/java/io/ray/api/call/TaskCaller.java (remote() call, L12-31)
• File: java/runtime/src/main/java/io/ray/runtime/task/NativeTaskSubmitter.java (JNI submission, L1-156)

Signature

// Factory method (on RayCall, inherited by Ray) — 1-param variant shown
public static <T0, R> TaskCaller<R> task(RayFunc1<T0, R> f, T0 t0)

// TaskCaller.remote() — submits the task
public ObjectRef<R> remote()

Overloaded variants exist for 0 to 6 parameters (Ray.task(func), Ray.task(func, t0), ..., Ray.task(func, t0, t1, t2, t3, t4, t5)).

Import

import io.ray.api.Ray;
import io.ray.api.ObjectRef;

I/O Contract

Inputs

Name	Type	Required	Description
f	RayFuncN<..., R>	Yes	A serializable function reference (method reference or lambda)
args	T0, T1, ...	Depends on arity	Function arguments; can include ObjectRef<T> for pass-by-reference
CallOptions	CallOptions	No	Optional resource requirements, task name, placement group (set via builder before .remote())

Outputs

Name	Type	Description
result	ObjectRef<R>	A future reference to the result object in the distributed object store

Usage Examples

Basic Task Submission

import io.ray.api.Ray;
import io.ray.api.ObjectRef;

public class TaskExample {
    public static String greet(String name) {
        return "Hello, " + name + "!";
    }

    public static void main(String[] args) {
        Ray.init();

        // Submit a remote task
        ObjectRef<String> ref = Ray.task(TaskExample::greet, "World").remote();

        // Get the result (blocks until ready)
        String result = ref.get();
        System.out.println(result); // "Hello, World!"

        Ray.shutdown();
    }
}

Chaining Tasks with ObjectRef

import io.ray.api.Ray;
import io.ray.api.ObjectRef;

public class ChainExample {
    public static int increment(int x) { return x + 1; }
    public static int doubleIt(int x) { return x * 2; }

    public static void main(String[] args) {
        Ray.init();

        // Chain tasks: increment(5) -> doubleIt(result)
        ObjectRef<Integer> step1 = Ray.task(ChainExample::increment, 5).remote();
        // Pass ObjectRef directly — no data movement until needed
        ObjectRef<Integer> step2 = Ray.task(ChainExample::doubleIt, step1).remote();

        System.out.println(step2.get()); // 12

        Ray.shutdown();
    }
}

Related Pages

Implements Principle

• Principle:Ray_project_Ray_Distributed_Task_Submission

Requires Environment

• Environment:Ray_project_Ray_Java_Build_Environment