将异步任务发送到在其他线程中运行的循环
问题描述
如何异步插入任务以在另一个线程中运行的asyncio
事件循环中运行?
我的动机是支持解释器中的交互式异步工作负载。我无法挡路主REPL帖子。
示例
我目前有缺陷的理解是,以下方法应该是可行的。为什么不是呢?实现上述目标的更好方法是什么?
import asyncio
from threading import Thread
loop = asyncio.new_event_loop()
def f(loop):
asyncio.set_event_loop(loop)
loop.run_forever()
t = Thread(target=f, args=(loop,))
t.start()
@asyncio.coroutine
def g():
yield from asyncio.sleep(1)
print('Hello, world!')
asyncio.async(g(), loop=loop)
解决方案
您必须使用call_soon_threadsafe
计划来自不同线程的回调:
import asyncio
from threading import Thread
loop = asyncio.new_event_loop()
def f(loop):
asyncio.set_event_loop(loop)
loop.run_forever()
t = Thread(target=f, args=(loop,))
t.start()
@asyncio.coroutine
def g():
yield from asyncio.sleep(1)
print('Hello, world!')
loop.call_soon_threadsafe(asyncio.async, g())
有关详细信息,请参阅https://docs.python.org/3/library/asyncio-dev.html#asyncio-multithreading。
编辑:支持异步工作负载的解释器示例
# vim: filetype=python3 tabstop=2 expandtab
import asyncio as aio
import random
@aio.coroutine
def async_eval(input_, sec):
yield from aio.sleep(sec)
print("")
try:
result = eval(input_)
except Exception as e:
print("< {!r} does not compute >".format(input_))
else:
print("< {!r} = {} >".format(input_, result))
@aio.coroutine
def main(loop):
while True:
input_ = yield from loop.run_in_executor(None, input, "> ")
if input_ == "quit":
break
elif input_ == "":
continue
else:
sec = random.uniform(5, 10)
print("< {!r} scheduled for execution in {:.02} sec>".format(input_, sec))
aio.async(async_eval(input_, sec))
loop = aio.get_event_loop()
loop.run_until_complete(main(loop))
loop.close()
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