Implementation:Ray project Ray Ray Init 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 initializing Ray with cross-language code search path configuration provided by the Ray Java SDK.

Description

The same Ray.init() call, but preceded by setting the ray.job.code-search-path system property. RayConfig (L79, L187-195) reads this property and populates codeSearchPath: List<String>, which is passed to the Raylet so workers can discover foreign-language code.

Usage

Set the ray.job.code-search-path system property before calling Ray.init(). The value is a colon-separated list of directories containing Python and C++ code.

Code Reference

Source Location

• Repository: ray-project/ray
• File: java/api/src/main/java/io/ray/api/Ray.java (L15-33)
• File: java/runtime/src/main/java/io/ray/runtime/config/RayConfig.java (L79, L187-195)

Signature

// Set code search path before init
System.setProperty("ray.job.code-search-path", "/path/to/python/code:/path/to/cpp/libs");
Ray.init();

Import

import io.ray.api.Ray;

I/O Contract

Inputs

Name	Type	Required	Description
ray.job.code-search-path	System property	Yes	Colon-separated list of directories with Python/C++ code

Outputs

Name	Type	Description
Ray.runtime	RayRuntime	Runtime with codeSearchPath configured for cross-language dispatch

Usage Examples

Initialize for Cross-Language

import io.ray.api.Ray;

public class CrossLangApp {
    public static void main(String[] args) {
        // Set path to Python/C++ code
        System.setProperty("ray.job.code-search-path", "/tmp/cross_lang_code");

        // Initialize Ray with cross-language support
        Ray.init();

        // Now PyFunction.of() and CppFunction.of() can be used
        // ...

        Ray.shutdown();
    }
}

Related Pages

Implements Principle

• Principle:Ray_project_Ray_Multi_Language_Cluster_Initialization

Requires Environment

• Environment:Ray_project_Ray_Java_Build_Environment