Enable including Java worker for ray start command (#3838)

python/ray/parameter.py

@@ -70,6 +70,9 @@ class RayParams(object):
             monitor the log files for all processes on this node and push their
             contents to Redis.
         autoscaling_config: path to autoscaling config file.
+        include_java (bool): If True, the raylet backend can also support
+            Java worker.
+        java_worker_options (str): The command options for Java worker.
         _internal_config (str): JSON configuration for overriding
             RayConfig defaults. For testing purposes ONLY.
     """
@@ -106,6 +109,8 @@ class RayParams(object):
                  temp_dir=None,
                  include_log_monitor=None,
                  autoscaling_config=None,
+                 include_java=False,
+                 java_worker_options=None,
                  _internal_config=None):
         self.object_id_seed = object_id_seed
         self.redis_address = redis_address
@@ -136,6 +141,8 @@ class RayParams(object):
         self.temp_dir = temp_dir
         self.include_log_monitor = include_log_monitor
         self.autoscaling_config = autoscaling_config
+        self.include_java = include_java
+        self.java_worker_options = java_worker_options
         self._internal_config = _internal_config
         self._check_usage()
 
@@ -146,7 +153,7 @@ class RayParams(object):
             kwargs: The keyword arguments to set corresponding fields.
         """
         for arg in kwargs:
-            if (hasattr(self, arg)):
+            if hasattr(self, arg):
                 setattr(self, arg, kwargs[arg])
             else:
                 raise ValueError("Invalid RayParams parameter in"
@@ -161,7 +168,7 @@ class RayParams(object):
             kwargs: The keyword arguments to set corresponding fields.
         """
         for arg in kwargs:
-            if (hasattr(self, arg)):
+            if hasattr(self, arg):
                 if getattr(self, arg) is None:
                     setattr(self, arg, kwargs[arg])
             else:
@@ -180,6 +187,10 @@ class RayParams(object):
                 "num_gpus instead.")
 
         if self.num_workers is not None:
-            raise Exception(
+            raise ValueError(
                 "The 'num_workers' argument is deprecated. Please use "
                 "'num_cpus' instead.")
+
+        if self.include_java is None and self.java_worker_options is not None:
+            raise ValueError("Should not specify `java-worker-options` "
+                             "without providing `include-java`.")