Actor 任务执行顺序

同步、单线程 Actor

在 Ray 中，一个 actor 从多个提交者（包括 driver 和 worker）接收任务。 对于来自同一提交者的任务，同步、单线程 actor 按照提交顺序执行它们。 换句话说，给定任务在之前提交的任务执行完之前不会执行。

Python

import ray

@ray.remote
class Counter:
    def __init__(self):
        self.value = 0

    def add(self, addition):
        self.value += addition
        return self.value

counter = Counter.remote()

# For tasks from the same submitter,
# they are executed according to submission order.
value0 = counter.add.remote(1)
value1 = counter.add.remote(2)

# Output: 1. The first submitted task is executed first.
print(ray.get(value0))
# Output: 3. The later submitted task is executed later.
print(ray.get(value1))

1
3

然而，actor 不保证来自不同提交者的任务的执行顺序。 例如，假设一个未满足的参数阻塞了之前提交的任务。 在这种情况下，actor 仍然可以执行由不同 worker 提交的任务。

Python

import time
import ray

@ray.remote
class Counter:
    def __init__(self):
        self.value = 0

    def add(self, addition):
        self.value += addition
        return self.value

counter = Counter.remote()

# Submit task from a worker
@ray.remote
def submitter(value):
    return ray.get(counter.add.remote(value))

# Simulate delayed result resolution.
@ray.remote
def delayed_resolution(value):
    time.sleep(5)
    return value

# Submit tasks from different workers, with
# the first submitted task waiting for
# dependency resolution.
value0 = submitter.remote(delayed_resolution.remote(1))
value1 = submitter.remote(2)

# Output: 3. The first submitted task is executed later.
print(ray.get(value0))
# Output: 2. The later submitted task is executed first.
print(ray.get(value1))

3
2

异步或线程 Actor

异步或线程 Actor 不保证 任务执行顺序。这意味着系统可能会执行一个任务， 即使之前提交的任务正在等待执行。

Python

import time
import ray

@ray.remote
class AsyncCounter:
    def __init__(self):
        self.value = 0

    async def add(self, addition):
        self.value += addition
        return self.value

counter = AsyncCounter.remote()

# Simulate delayed result resolution.
@ray.remote
def delayed_resolution(value):
    time.sleep(5)
    return value

# Submit tasks from the driver, with
# the first submitted task waiting for
# dependency resolution.
value0 = counter.add.remote(delayed_resolution.remote(1))
value1 = counter.add.remote(2)

# Output: 3. The first submitted task is executed later.
print(ray.get(value0))
# Output: 2. The later submitted task is executed first.
print(ray.get(value1))

3
2