Implementation:Ray project Ray Ray Task Cross Language

Knowledge Sources	Ray Ray Cross-Language
Domains	Distributed_Computing, Cross_Language_Interop
Last Updated	2026-02-13 17:00 GMT

Overview

Concrete tool for submitting tasks to foreign-language workers via function descriptors provided by the Ray Java SDK.

Description

When Ray.task() receives a PyFunction or CppFunction descriptor (instead of a Java method reference), AbstractRayRuntime.call() creates a PyFunctionDescriptor or CppFunctionDescriptor that implements FunctionDescriptor.getLanguage() returning Language.PYTHON or Language.CPP. The Raylet routes the task to the appropriate language worker, which loads the function from the code search path.

The same pattern applies to actors: Ray.actor() with PyActorClass or CppActorClass creates cross-language actor instances.

Usage

Use the same Ray.task() and Ray.actor() APIs with cross-language descriptors instead of Java method references.

Code Reference

Source Location

• Repository: ray-project/ray
• File: java/runtime/src/main/java/io/ray/runtime/AbstractRayRuntime.java (L1-456)
• File: java/runtime/src/main/java/io/ray/runtime/functionmanager/PyFunctionDescriptor.java (L9-55)
• File: java/runtime/src/main/java/io/ray/runtime/functionmanager/CppFunctionDescriptor.java (L9-55)

Signature

// Python function task
Ray.task(PyFunction<R> pyFunction, args...).remote() -> ObjectRef<R>

// C++ function task
Ray.task(CppFunction<R> cppFunction, args...).remote() -> ObjectRef<R>

// Python actor
Ray.actor(PyActorClass pyActorClass, args...).remote() -> PyActorHandle

// C++ actor
Ray.actor(CppActorClass cppActorClass, args...).remote() -> CppActorHandle

Import

import io.ray.api.Ray;
import io.ray.api.ObjectRef;
import io.ray.api.function.PyFunction;
import io.ray.api.function.CppFunction;

I/O Contract

Inputs

Name	Type	Required	Description
descriptor	PyFunction/CppFunction/PyActorClass/CppActorClass	Yes	Cross-language function/actor descriptor
args	Object...	Depends	Arguments (must be MessagePack-compatible for cross-language)

Outputs

Name	Type	Description
result	ObjectRef<R>	Future reference to the cross-language result
actorHandle	PyActorHandle/CppActorHandle	Handle for cross-language actors

Usage Examples

Call Python Function

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

System.setProperty("ray.job.code-search-path", "/path/to/python/code");
Ray.init();

// Call Python function
ObjectRef<byte[]> result = Ray.task(
    PyFunction.of("my_module", "process_data"),
    "input_data"
).remote();

byte[] output = result.get();
Ray.shutdown();

Create Python Actor

import io.ray.api.Ray;
import io.ray.api.PyActorHandle;
import io.ray.api.function.PyActorClass;
import io.ray.api.function.PyFunction;

PyActorHandle actor = Ray.actor(
    PyActorClass.of("my_module", "Counter")
).remote();

// Call actor method
ObjectRef<Object> result = actor.task(
    PyFunction.of("my_module", "Counter.increment")
).remote();

Related Pages

Implements Principle

• Principle:Ray_project_Ray_Cross_Language_Task_Submission

Requires Environment

• Environment:Ray_project_Ray_Java_Build_Environment