Asyncio标准失败

Question

我试图掌握使用异步加速调用外部工具来分析多个音频文件的过程。我正在编写windows，python 3.6 (anaconda安装)，而我在这里遇到的问题是，调用似乎没有等待，或者结果从来没有通过stdout接收到。

有什么想法吗？

import os
import asyncio

external_tool = r"C:\path\to\external\tool.exe"

def filepaths_generator(root):
    '''
    Simple generator to yield filepaths
    '''
    for path, dirs, files in os.walk(root):
        for f in files:
            yield os.path.join(path,f)


async def async_subprocess_command(*args):
    '''
    A function to run the asyncio subprocess call
    '''
    # Create subprocess
    process = asyncio.create_subprocess_exec(
        *args,
        # stdout must a pipe to be accessible as process.stdout
        stdout=asyncio.subprocess.PIPE)
    # Wait for the subprocess to finish
    stdout, stderr = await process.communicate()
    # Return stdout
    return stdout.decode().strip()

async def add_external_tool_data_to_dict(filepath):
    external_tool_data = await async_subprocess_command(external_tool,filepath)
    metadata_dict[filepath] = external_tool_data
    return

metadata_dict = {}

loop = asyncio.get_event_loop()
#loop = asyncio.ProactorEventLoop() - Tried this, it doesn't help!

filepaths = filepaths_generator(r"C:\root\path")
tasks = []

for filepath in filepaths:
    #Create tasks in for the loop and add to a list
    task = loop.create_task(add_external_tool_data_to_dict(filepath))
    tasks.append(task)
#Run the tasks
loop.run_until_complete(asyncio.wait(tasks))

loop.close()
print(metadata_dict)

Answer 1

首先是这

在Windows上，默认事件循环是不支持子进程的SelectorEventLoop。应该使用ProactorEventLoop代替

在Windows上使用它的示例：

import asyncio, sys

if sys.platform == 'win32':
    loop = asyncio.ProactorEventLoop()
    asyncio.set_event_loop(loop)

首先，我将切换到这个备用事件循环。

Answer 2

根据Gerrat的评论，解决方案是使用ProactorEventLoop，然后再添加一行：

loop = asyncio.ProactorEventLoop()
asyncio.set_event_loop(loop)