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README.rst

This directory contains the java worker, with the following components.

  • java/api: Ray API definition
  • java/common: utilities
  • java/runtime-common: common implementation of the runtime in worker
  • java/runtime-dev: a pure-java mock implementation of the runtime for fast development
  • java/runtime-native: a native implementation of the runtime
  • java/test: various tests
  • src/local_scheduler/lib/java: JNI client library for local scheduler
  • src/plasma/lib/java: JNI client library for plasma storage

Quick start

Starting Ray

Ray.init();

Read and write remote objects

Each remote object is considered a RayObject<T> where T is the type for this object. You can use Ray.put and RayObject<T>.get to write and read the objects.

Integer x = 1;
RayObject<Integer> obj = Ray.put(x);
Integer x1 = obj.get();
assert (x.equals(x1));

Remote functions

Here is an ordinary java code piece for composing hello world example.

public class ExampleClass {
    public static void main(String[] args) {
        String str1 = add("hello", "world");
        String str = add(str1, "example");
        System.out.println(str);
    }
    public static String add(String a, String b) {
        return a + " " + b;
    }
}

We use @RayRemote to indicate that a function is remote, and use Ray.call to invoke it. The result from the latter is a RayObject<R> where R is the return type of the target function. The following shows the changed example with add annotated, and correspondent calls executed on remote machines.

public class ExampleClass {
    public static void main(String[] args) {
        Ray.init();
        RayObject<String> objStr1 = Ray.call(ExampleClass::add, "hello", "world");
        RayObject<String> objStr2 = Ray.call(ExampleClass::add, objStr1, "example");
        String str = objStr2.get();
        System.out.println(str);
    }

    @RayRemote
    public static String add(String a, String b) {
        return a + " " + b;
    }
}

More information