Implementation:Ray project Ray NodeInfo

Knowledge Sources	Ray
Domains	Distributed_Computing, Java_Runtime
Last Updated	2026-02-13 16:00 GMT

Overview

Immutable data class representing the metadata and state of a single node in a Ray cluster.

Description

NodeInfo is a plain data class with all fields declared public final, exposing node identity, network addresses, liveness status, available resources, and user-defined labels. The constructor accepts nine parameters and directly assigns them. A toString() override provides a human-readable representation for logging and debugging.

Usage

Use NodeInfo to inspect cluster topology information returned by RuntimeContext.getAllNodeInfo(). It gives Java applications visibility into which nodes exist, whether they are alive, what resources (CPU, GPU, memory) they offer, and how they can be reached via sockets, enabling resource-aware scheduling decisions and cluster monitoring from user code.

Code Reference

Source Location

• Repository: Ray
• File: java/api/src/main/java/io/ray/api/runtimecontext/NodeInfo.java

Signature

public class NodeInfo {

  public final UniqueId nodeId;
  public final String nodeAddress;
  public final String nodeHostname;
  public final int nodeManagerPort;
  public final String objectStoreSocketName;
  public final String rayletSocketName;
  public final boolean isAlive;
  public final Map<String, Double> resources;
  public final Map<String, String> labels;

  public NodeInfo(
      UniqueId nodeId,
      String nodeAddress,
      String nodeHostname,
      int nodeManagerPort,
      String objectStoreSocketName,
      String rayletSocketName,
      boolean isAlive,
      Map<String, Double> resources,
      Map<String, String> labels) { ... }

  public String toString() { ... }
}

Import

import io.ray.api.runtimecontext.NodeInfo;

I/O Contract

Input (Constructor)

Parameter	Type	Description
nodeId	UniqueId	Unique identifier for the node
nodeAddress	String	IP address of the node
nodeHostname	String	Hostname of the node
nodeManagerPort	int	Port for the node manager (raylet)
objectStoreSocketName	String	RPC socket name for the object store
rayletSocketName	String	RPC socket name for the raylet
isAlive	boolean	Whether the node is currently alive
resources	Map<String, Double>	Available resources (e.g., CPU, GPU, memory)
labels	Map<String, String>	User-defined labels attached to the node

Output

Method	Return Type	Description
toString()	String	Human-readable string representation of all node fields

Usage Examples

// Retrieve all node information from the runtime context
RuntimeContext ctx = Ray.getRuntimeContext();
List<NodeInfo> nodes = ctx.getAllNodeInfo();

for (NodeInfo node : nodes) {
    System.out.println("Node: " + node.nodeId);
    System.out.println("Address: " + node.nodeAddress);
    System.out.println("Alive: " + node.isAlive);
    System.out.println("Resources: " + node.resources);
    System.out.println("Labels: " + node.labels);
}

// Filter for alive nodes with GPU resources
List<NodeInfo> gpuNodes = nodes.stream()
    .filter(n -> n.isAlive && n.resources.containsKey("GPU"))
    .collect(Collectors.toList());

Related Pages

• Environment:Ray_project_Ray_Java_Build_Environment