Actor 任务执行顺序

同步单线程 Actor

在 Ray 中，Actor 接收来自多个提交者（包括驱动程序和 worker）的任务。对于来自同一提交者的任务，如果 Actor 任务从未重试，同步单线程 Actor 将按照提交顺序执行它们。换句话说，给定任务不会执行，直到来自同一提交者之前提交的任务执行完毕。对于 max_task_retries 设置为非零值的 Actor，在任务重试发生时，任务执行顺序不保证。

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 仍然可以执行由其他 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

异步或多线程 Actor

异步或多线程 Actor 不保证任务执行顺序。这意味着即使之前提交的任务仍在等待执行，系统也可能执行某个任务。

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