命名 Actor#

Actor 在其命名空间内可以被赋予一个唯一的名称。这允许你从 Ray 集群中的任何作业中检索该 Actor。如果你无法直接将 Actor handle 传递给需要它的任务，或者你试图访问由另一个 driver 启动的 Actor，这会很有用。请注意，如果不存在指向该 Actor 的 handle，该 Actor 仍会被垃圾回收。更多详情请参阅Actor 生命周期。

import ray

@ray.remote
class Counter:
    pass

# Create an actor with a name
counter = Counter.options(name="some_name").remote()

# Retrieve the actor later somewhere
counter = ray.get_actor("some_name")

// Create an actor with a name.
ActorHandle<Counter> counter = Ray.actor(Counter::new).setName("some_name").remote();

...

// Retrieve the actor later somewhere
Optional<ActorHandle<Counter>> counter = Ray.getActor("some_name");
Assert.assertTrue(counter.isPresent());

// Create an actor with a globally unique name
ActorHandle<Counter> counter = ray::Actor(CreateCounter).SetGlobalName("some_name").Remote();

...

// Retrieve the actor later somewhere
boost::optional<ray::ActorHandle<Counter>> counter = ray::GetGlobalActor("some_name");

我们还在 C++ 中支持非全局命名 Actor，这意味着 Actor 名称仅在作业内有效，不能从其他作业访问该 Actor。

// Create an actor with a job-scope-unique name
ActorHandle<Counter> counter = ray::Actor(CreateCounter).SetName("some_name").Remote();

...

// Retrieve the actor later somewhere in the same job
boost::optional<ray::ActorHandle<Counter>> counter = ray::GetActor("some_name");

注意

命名 Actor 通过命名空间限定范围。如果未指定命名空间，它们将默认放置在匿名命名空间中。

import ray

@ray.remote
class Actor:
  pass

# driver_1.py
# Job 1 creates an actor, "orange" in the "colors" namespace.
ray.init(address="auto", namespace="colors")
Actor.options(name="orange", lifetime="detached").remote()

# driver_2.py
# Job 2 is now connecting to a different namespace.
ray.init(address="auto", namespace="fruit")
# This fails because "orange" was defined in the "colors" namespace.
ray.get_actor("orange")
# You can also specify the namespace explicitly.
ray.get_actor("orange", namespace="colors")

# driver_3.py
# Job 3 connects to the original "colors" namespace
ray.init(address="auto", namespace="colors")
# This returns the "orange" actor we created in the first job.
ray.get_actor("orange")

import ray

class Actor {
}

// Driver1.java
// Job 1 creates an actor, "orange" in the "colors" namespace.
System.setProperty("ray.job.namespace", "colors");
Ray.init();
Ray.actor(Actor::new).setName("orange").remote();

// Driver2.java
// Job 2 is now connecting to a different namespace.
System.setProperty("ray.job.namespace", "fruits");
Ray.init();
// This fails because "orange" was defined in the "colors" namespace.
Optional<ActorHandle<Actor>> actor = Ray.getActor("orange");
Assert.assertFalse(actor.isPresent());  // actor.isPresent() is false.

// Driver3.java
System.setProperty("ray.job.namespace", "colors");
Ray.init();
// This returns the "orange" actor we created in the first job.
Optional<ActorHandle<Actor>> actor = Ray.getActor("orange");
Assert.assertTrue(actor.isPresent());  // actor.isPresent() is true.

获取或创建命名 Actor#

一个常见的用例是仅当 Actor 不存在时才创建它。Ray 为 Actor 创建提供了一个开箱即用的 get_if_exists 选项。在通过 .options() 为 Actor 设置名称后，此方法可用。

如果 Actor 已存在，将返回该 Actor 的 handle 并忽略参数。否则，将使用指定的参数创建一个新的 Actor。

import ray


@ray.remote
class Greeter:
    def __init__(self, value):
        self.value = value

    def say_hello(self):
        return self.value


# Actor `g1` doesn't yet exist, so it is created with the given args.
a = Greeter.options(name="g1", get_if_exists=True).remote("Old Greeting")
assert ray.get(a.say_hello.remote()) == "Old Greeting"

# Actor `g1` already exists, so it is returned (new args are ignored).
b = Greeter.options(name="g1", get_if_exists=True).remote("New Greeting")
assert ray.get(b.say_hello.remote()) == "Old Greeting"

// This feature is not yet available in Java.

// This feature is not yet available in C++.

Actor 生命周期#

另外，Actor 的生命周期可以与作业解耦，允许 Actor 在作业的 driver 进程退出后仍然存在。我们将这些 Actor 称为分离的 (detached)。

counter = Counter.options(name="CounterActor", lifetime="detached").remote()

即使运行上述脚本的 driver 退出后，CounterActor 仍会保持活动。因此，可以在不同的 driver 中运行以下脚本。

counter = ray.get_actor("CounterActor")

请注意，Actor 可以被命名但不分离。如果我们只指定了名称但没有指定 lifetime="detached"，那么只要原始 driver 仍在运行，就可以检索到 CounterActor。

System.setProperty("ray.job.namespace", "lifetime");
Ray.init();
ActorHandle<Counter> counter = Ray.actor(Counter::new).setName("some_name").setLifetime(ActorLifetime.DETACHED).remote();

即使运行上述进程的 driver 退出后，CounterActor 仍会保持活动。因此，可以在不同的 driver 中运行以下代码。

System.setProperty("ray.job.namespace", "lifetime");
Ray.init();
Optional<ActorHandle<Counter>> counter = Ray.getActor("some_name");
Assert.assertTrue(counter.isPresent());

Actor 生命周期自定义功能尚未在 C++ 中实现。

与普通 Actor 不同，分离的 Actor 不会被 Ray 自动垃圾回收。一旦你确定不再需要分离的 Actor，必须手动销毁它们。为此，使用 ray.kill 来手动终止 Actor。调用此方法后，可以重复使用 Actor 的名称。