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Richard Liaw
0bab8ed95c
## What do these changes do? This PR exposes the CL option for using a config parameter. This is important for certain tests (i.e., FT tests that removing nodes) to run quickly. Note that this is bad practice and should be replaced with GFLAGS or some equivalent as soon as possible. #3239 depends on this. TODO: - [x] Add documentation to method arguments before merging. - [x] Add test to verify this works? ## Related issue number
Quick start
===========
Configuration
-------------
Ray will read your configurations in the following order:
* Java system properties: e.g., ``-Dray.home=/path/to/ray``.
* A ``ray.conf`` file in the classpath: `example <https://github.com/ray-project/ray/blob/master/java/example.conf>`_.
* Customise your own ``ray.conf`` path using system property ``-Dray.config=/path/to/ray.conf``
For all available config items and default values, see `this file <https://github.com/ray-project/ray/blob/master/java/runtime/src/main/resources/ray.default.conf>`_.
Starting Ray
------------
.. code:: java
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.
.. code:: java
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``.
.. code:: java
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.
.. code:: java
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
================
- `Installation <https://github.com/ray-project/ray/tree/master/java/doc/installation.rst>`_
- `API document <https://github.com/ray-project/ray/tree/master/java/doc/api.rst>`_
- `Tutorial <https://github.com/ray-project/ray/tree/master/java/tutorial>`_