ray/doc/source/ray-client.rst
2021-01-13 21:28:54 -08:00

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**********
Ray Client
**********
.. note::
This feature is still in beta and subject to changes.
===========
Basic usage
===========
While in beta, the server is available as an executable module. To start the server, run
``python -m ray.util.client.server [--host host_ip] [--port port] [--redis-address address] [--redis-password password]``
This runs ``ray.init()`` with default options and exposes the client gRPC port at ``host_ip:port`` (by default, ``0.0.0.0:50051``). Providing ``redis-address`` and ``redis-password`` will be passed into ``ray.init()`` when the server starts, allowing connection to an existing Ray cluster, as per the `cluster setup <cluster/index.html>`_ instructions.
From here, another Ray script can access that server from a networked machine with ``ray.util.connect()``
.. code-block:: python
import ray
import ray.util
ray.util.connect("0.0.0.0:50051") # replace with the appropriate host and port
# Normal Ray code follows
@ray.remote
def f(x):
return x ** x
do_work.remote(2)
#....
When the client disconnects, any object or actor references held by the server on behalf of the client are dropped, as if directly disconnecting from the cluster
===================
``RAY_CLIENT_MODE``
===================
Because Ray client mode affects the behavior of the Ray API, larger scripts or libraries imported before ``ray.util.connect()`` may not realize they're in client mode. This feature is being tracked with `issue #13272 <https://github.com/ray-project/ray/issues/13272>`_ but the workaround here is provided for beta users.
One option is to defer the imports from a ``main`` script that calls ``ray.util.connect()`` first. However, some older scripts or libraries might not support that.
Therefore, an environment variable is also available to force a Ray program into client mode: ``RAY_CLIENT_MODE`` An example usage:
.. code-block:: bash
RAY_CLIENT_MODE=1 python my_ray_program.py
===================================
Programatically creating the server
===================================
For larger use-cases, it may be desirable to connect remote Ray clients to an existing Ray environment. The server can be started separately via
.. code-block:: python
from ray.util.client.server import serve
server = serve("0.0.0.0:50051")
# Server does some work
# ...
# Time to clean up
server.stop(0)