[英]Multiprocess Queue synchronization with asyncio
我想從asyncio
3.7 的兄弟進程中運行的異步循環中收集數據
理想情況下,我會使用multiprocess.JoinableQueue
,中繼其join()
調用以進行同步。
但是,它的同步原語完全阻止了事件循環(有關示例,請參見下面我的部分回答)。
說明原型:
class MP_GatherDict(dict):
'''A per-process dictionary which can be gathered from a single one'''
def __init__(self):
self.q = multiprocess.JoinableQueue()
super().__init__()
async def worker_process_server(self):
while True:
(await?) self.q.put(dict(self)) # Put a shallow copy
(await?) self.q.join() # Wait for it to be gathered
async def gather(self):
all_dicts = []
while not self.q.empty():
all_dicts.append(await self.q.get())
self.q.task_done()
return all_dicts
請注意, put->get->join->put
流程可能無法按預期工作,但這個問題實際上是關於在asyncio
事件循環中使用multiprocess
進程原語......
那么問題就是如何最好地await
來自 asyncio 事件循環的multiprocess
進程原語?
此測試顯示multiprocess.Queue.get()
阻止整個事件循環:
mp_q = mp.JoinableQueue()
async def mp_queue_wait():
try:
print('Queue:',mp_q.get(timeout=2))
except Exception as ex:
print('Queue:',repr(ex))
async def main_loop_task():
task = asyncio.get_running_loop().create_task(mp_queue_wait())
for i in range(3):
print(i, os.times())
await asyncio.sleep(1)
await task
print(repr(task))
asyncio.run(main_loop_task())
誰的輸出是:
0 posix.times_result(user=0.41, system=0.04, children_user=0.0, children_system=0.0, elapsed=17208620.18)
Queue: Empty()
1 posix.times_result(user=0.41, system=0.04, children_user=0.0, children_system=0.0, elapsed=17208622.18)
2 posix.times_result(user=0.41, system=0.04, children_user=0.0, children_system=0.0, elapsed=17208623.18)
<Task finished coro=<mp_queue_wait() done,...> result=None>
所以我看asyncio.loop.run_in_executor()作為下一個可能的答案,但是為此產生一個執行器/線程似乎有點過分......
這是使用默認執行程序的相同測試:
async def mp_queue_wait():
try:
result = await asyncio.get_running_loop().run_in_executor(None,mp_q.get,True,2)
except Exception as ex:
result = ex
print('Queue:',repr(result))
return result
並且(期望的)結果:
0 posix.times_result(user=0.36, system=0.02, children_user=0.0, children_system=0.0, elapsed=17210674.65)
1 posix.times_result(user=0.37, system=0.02, children_user=0.0, children_system=0.0, elapsed=17210675.65)
Queue: Empty()
2 posix.times_result(user=0.37, system=0.02, children_user=0.0, children_system=0.0, elapsed=17210676.66)
<Task finished coro=<mp_queue_wait() done, defined at /home/apozuelo/Documents/5G_SBA/Tera5G/services/db.py:211> result=Empty()>
這有點晚了,但是。
您需要圍繞mp.JoinableQueue()
創建一個異步包裝器,因為get()
和put()
都會阻塞整個過程 (GIL)。
有兩種方法:
asyncio.sleep()
和get_nowait()
、 put_nowait()
方法。我選擇了選項 2,因為它很簡單。
from queue import Queue, Full, Empty
from typing import Any, Generic, TypeVar
from asyncio import sleep
T= TypeVar('T')
class AsyncQueue(Generic[T]):
"""Async wrapper for queue.Queue"""
SLEEP: float = 0.01
def __init__(self, queue: Queue[T]):
self._Q : Queue[T] = queue
async def get(self) -> T:
while True:
try:
return self._Q.get_nowait()
except Empty:
await sleep(self.SLEEP)
async def put(self, item: T) -> None:
while True:
try:
self._Q.put_nowait(item)
return None
except Full:
await sleep(self.SLEEP)
def task_done(self) -> None:
self._Q.task_done()
return None
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.