我设法编写了一个相当愚蠢的错误,它会让我的一个请求处理程序运行一个非常慢的数据库查询。
有趣的一点是,我注意到即使很长时间围攻完成后,龙卷风仍然在通过请求(有时是90年代后)。 (评论 - >我不是100%确定Siege的运作方式,但我确信它已经关闭了连接......)
我的问题分为两部分: - 当客户端关闭连接时,Tornado会取消请求处理程序吗? - 有没有办法在Tornado中超时请求处理程序?
我仔细阅读了代码,似乎找不到任何东西。即使我的请求处理程序在上面的错误中异步运行,待处理请求的数量也会增加,这会降低应用程序的速度,最好关闭连接。
答案 0 :(得分:5)
当客户端断开连接时,Tornado不会自动关闭请求处理程序。但是,您可以覆盖on_connection_close
以在客户端丢弃时收到警报,这样您就可以取消终端上的连接。可以使用上下文管理器(或装饰器)来处理设置超时以处理请求;使用tornado.ioloop.IOLoop.add_timeout
来安排一些方法,将timeout
作为上下文管理器的__enter__
的一部分后运行的请求超时,然后在__exit__
块中取消该回调上下文管理器。这是一个展示这两个想法的例子:
import time
import contextlib
from tornado.ioloop import IOLoop
import tornado.web
from tornado import gen
@gen.coroutine
def async_sleep(timeout):
yield gen.Task(IOLoop.instance().add_timeout, time.time() + timeout)
@contextlib.contextmanager
def auto_timeout(self, timeout=2): # Seconds
handle = IOLoop.instance().add_timeout(time.time() + timeout, self.timed_out)
try:
yield handle
except Exception as e:
print("Caught %s" % e)
finally:
IOLoop.instance().remove_timeout(handle)
if not self._timed_out:
self.finish()
else:
raise Exception("Request timed out") # Don't continue on passed this point
class TimeoutableHandler(tornado.web.RequestHandler):
def initialize(self):
self._timed_out = False
def timed_out(self):
self._timed_out = True
self.write("Request timed out!\n")
self.finish() # Connection to client closes here.
# You might want to do other clean up here.
class MainHandler(TimeoutableHandler):
@gen.coroutine
def get(self):
with auto_timeout(self): # We'll timeout after 2 seconds spent in this block.
self.sleeper = async_sleep(5)
yield self.sleeper
print("writing") # get will abort before we reach here if we timed out.
self.write("hey\n")
def on_connection_close(self):
# This isn't the greatest way to cancel a future, since it will not actually
# stop the work being done asynchronously. You'll need to cancel that some
# other way. Should be pretty straightforward with a DB connection (close
# the cursor/connection, maybe?)
self.sleeper.set_exception(Exception("cancelled"))
application = tornado.web.Application([
(r"/test", MainHandler),
])
application.listen(8888)
IOLoop.instance().start()
答案 1 :(得分:0)
解决此问题的另一种方法是使用gen.with_timeout:
import time
from tornado import gen
from tornado.util import TimeoutError
class MainHandler
@gen.coroutine
def get(self):
try:
# I'm using gen.sleep here but you can use any future in this place
yield gen.with_timeout(time.time() + 2, gen.sleep(5))
self.write("This will never be reached!!")
except TimeoutError as te:
logger.warning(te.__repr__())
self.timed_out()
def timed_out(self):
self.write("Request timed out!\n")
我喜欢contextlib解决方案所处理的方式,但是我一直在记录剩余的日志。
原生协程解决方案是:
async def get(self):
try:
await gen.with_timeout(time.time() + 2, gen.sleep(5))
self.write("This will never be reached!!")
except TimeoutError as te:
logger.warning(te.__repr__())
self.timed_out()