我试图让Tornado使用aio_etcd aio_etcd documentation here
我希望获得Tornado Coroutine中的锁定。我写了以下代码。文档中的示例使用＆＃39; await＆＃39;然而，我用产量替换了这个，因为我使用@tornado.gen.coroutine装饰我不确定这是否正确。我通过以下代码得到以下崩溃：
raise RuntimeError('Timeout context manager should be used '
RuntimeError: Timeout context manager should be used inside a task
ERROR:tornado.access:500 GET / (::1) 6.33ms
...
import tornado.web
import tornado.httpserver
import tornado.httpclient
import tornado.ioloop
import tornado.options
import tornado.gen
import tornado.auth
from multiprocessing import Process
import aio_etcd as etcd
def run_process(port):
app=Application()
server=tornado.httpserver.HTTPServer(app)
server.listen(port)
tornado.ioloop.IOLoop.current().start()
class MainHandler(tornado.web.RequestHandler):
@tornado.gen.coroutine
def get(self):
print("in function")
l = etcd.Lock(self.application.etcdClient, "L")
# Use the lock object:
yield from l.acquire(blocking=True, lock_ttl=None)
print("got lock")
yield tornado.gen.sleep(30)
yield from l.release()
print("releasing lock")
class Application(tornado.web.Application):
def __init__(self):
handlers = [
(r"/",MainHandler),
]
self.etcdClient=etcd.Client()
# Settings dict for Application
settings = {
}
tornado.web.Application.__init__(self,handlers,debug=True,**settings)
if __name__ =='__main__':
Process(target=run_process,args=(8000,)).start()
Process(target=run_process,args=(8001,)).start()
同样在我的代码中，我没有使用新的异步键盘而是我的所有Tornado协同例程都使用@tornado.gen.coroutine进行修饰。有人可以解释为什么使用yield关键字而不是yield in in in龙卷风的常规以及为什么这些不同。有谁知道我如何在Tornado中使用此代码？
使用asyncio更新代码：
import tornado.web
import tornado.httpserver
import tornado.httpclient
import tornado.ioloop
import tornado.options
import tornado.gen
import tornado.auth
import asyncio
from multiprocessing import Process
import aio_etcd as etcd
import tornado.platform.asyncio
def run_process(port):
tornado.platform.asyncio.AsyncIOMainLoop().install()
app=Application()
server=tornado.httpserver.HTTPServer(app)
server.listen(port)
asyncio.get_event_loop().run_forever()
class MainHandler(tornado.web.RequestHandler):
async def get(self):
print("here")
lock = etcd.Lock(self.application.etcdClient, "hello")
# Use the lock object:
await asyncio.ensure_future(lock.acquire())
state = await asyncio.ensure_future(lock.is_locked())
print("lock state")
print(state)
class Application(tornado.web.Application):
def __init__(self):
handlers = [
(r"/",MainHandler),
]
self.etcdClient=etcd.Client()
# Settings dict for Application
settings = {
}
tornado.web.Application.__init__(self,handlers,debug=True,**settings)
if __name__ =='__main__':
Process(target=run_process,args=(8000,)).start()
Process(target=run_process,args=(8001,)).start()
崩溃追踪：
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/tornado/web.py", line 1469, in _execute
result = yield result
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/tornado/gen.py", line 1015, in run
value = future.result()
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/tornado/concurrent.py", line 237, in result
raise_exc_info(self._exc_info)
File "<string>", line 3, in raise_exc_info
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/tornado/gen.py", line 1021, in run
yielded = self.gen.throw(*exc_info)
File "<string>", line 6, in _wrap_awaitable
File "check3.py", line 27, in get
await asyncio.ensure_future(lock.acquire())
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/asyncio/futures.py", line 361, in __iter__
yield self # This tells Task to wait for completion.
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/tornado/gen.py", line 1015, in run
value = future.result()
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/tornado/concurrent.py", line 237, in result
raise_exc_info(self._exc_info)
File "<string>", line 3, in raise_exc_info
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/asyncio/tasks.py", line 239, in _step
result = coro.send(None)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/aio_etcd-0.4.3.1-py3.5.egg/aio_etcd/lock.py", line 67, in acquire
res = await self.client.write(self.path, self.uuid, ttl=lock_ttl, append=True)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/aio_etcd-0.4.3.1-py3.5.egg/aio_etcd/client.py", line 449, in write
response = await self.api_execute(path, method, params=params)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/aio_etcd-0.4.3.1-py3.5.egg/aio_etcd/client.py", line 780, in wrapper
response = await payload(self, path, method, params=params)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/aiohttp-1.1.1-py3.5-macosx-10.6-intel.egg/aiohttp/client.py", line 553, in __await__
resp = yield from self._coro
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/aiohttp-1.1.1-py3.5-macosx-10.6-intel.egg/aiohttp/client.py", line 198, in _request
proxy=proxy, proxy_auth=proxy_auth, timeout=timeout)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/aiohttp-1.1.1-py3.5-macosx-10.6-intel.egg/aiohttp/client_reqrep.py", line 79, in __init__
url2 = url.with_query(params)
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/yarl-0.5.3-py3.5-macosx-10.6-intel.egg/yarl/__init__.py", line 607, in with_query
for k, v in query.items())
File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/yarl-0.5.3-py3.5-macosx-10.6-intel.egg/yarl/__init__.py", line 607, in <genexpr>
for k, v in query.items())
File "yarl/_quoting.pyx", line 46, in yarl._quoting._quote (yarl/_quoting.c:1384)
TypeError: Argument should be str
答案 0 :(得分：2)
正如Jesse所说，一些asyncio库特别需要asyncio，目前不能与Tornado一起使用（未来版本的Tornado将改善这种兼容性）。但是，有一种解决方法并不需要远离龙卷风。在屈服或等待之前，只需将aio_etcd与asyncio.ensure_future()的任何电话联系起来。以下是aiohttp的示例（因为我没有etcd服务器进行测试）：
from tornado.platform.asyncio import AsyncIOMainLoop
AsyncIOMainLoop().install()
from tornado.ioloop import IOLoop
import aiohttp
import asyncio
async def main():
print(await asyncio.ensure_future(aiohttp.get('https://www.google.com')))
IOLoop.current().run_sync(main)
答案 1 :(得分：1)
为asyncio编写的许多库都可以与Tornado互操作。不幸的是，有些库，比如aio_etcd，不是，因为它们以特定于asyncio的方式实现超时。请参阅aiohttp issue 877 - 此问题描述了aiohttp.Timeout中的问题。该代码从aiohttp分离到单独的async_timeout包，并且这个单独的包仍然与Tornado不兼容。这是aio_etcd用来实现超时的，所以aio_etcd也与Tornado不兼容。
长期解决方法是在aio_etcd's tracker中打开一个要求Tornado兼容性的错误。如果timeout=None，aio_etcd可以使用async_timeout not 来提供Tornado兼容性。这与in this comment的建议相同。请在打开故障单时链接到此StackOverflow问题。
短期修复是使用asyncio及其Web框架aiohttp而不是Tornado：
from multiprocessing import Process
import asyncio
from aiohttp import web
import aio_etcd as etcd
# Don't create this in the parent process, wait for Process() to spawn child.
etcd_client = None
async def handle(request):
print("in function")
l = etcd.Lock(etcd_client, "L")
# Use the lock object:
await l.acquire(blocking=True, lock_ttl=None)
print("got lock")
await asyncio.sleep(30)
await l.release()
print("releasing lock")
return web.Response(text='ok')
def run_process(port):
global etcd_client
app = web.Application(debug=True)
app.router.add_get('/', handle)
# Create AFTER multiprocess starts this child process.
etcd_client = etcd.Client()
web.run_app(app, port=port)
if __name__ == '__main__':
# run_process(8000)
Process(target=run_process, args=(8000,)).start()
Process(target=run_process, args=(8001,)).start()
aiohttp docs to get you started are here
回答你的其他问题：龙卷风在gen.coroutine中使用了多年的“收益率”。它的设计影响了asyncio的协同程序，但它们在Python 3.4中使用了“yield from”。 Guido's explanation of the difference between "yield" and "yield from" is here，这当然很有趣，但现在不那么重要了。在Python 3.5中，“yield from”被PEP 492 -- Coroutines with async and await syntax取代。
如果您的代码永远不需要在早于3.5的Python上运行，只需使用“async”和“await”而不是“coroutine”装饰器和“yield”（在Tornado中）或“yield from”（在asyncio中）。对你而言，我知道你正在运行Python 3.5因为aio_etcd需要它，所以只需使用async并等待我在上面的代码中演示。