[英]Error when using twisted and greenlets
I'm trying to use twisted with greenlets, so I can write synchronous looking code in twisted without using inlineCallbacks. 我正在尝试将Twisted与greenlet一起使用,因此我可以在不使用inlineCallbacks的情况下以twisted形式编写同步外观的代码。
Here is my code: 这是我的代码:
import time, functools
from twisted.internet import reactor, threads
from twisted.internet.defer import Deferred
from functools import wraps
import greenlet
def make_async(func):
@wraps(func)
def wrapper(*pos, **kwds):
d = Deferred()
def greenlet_func():
try:
rc = func(*pos, **kwds)
d.callback(rc)
except Exception, ex:
print ex
d.errback(ex)
g = greenlet.greenlet(greenlet_func)
g.switch()
return d
return wrapper
def sleep(t):
print "sleep(): greenelet:", greenlet.getcurrent()
g = greenlet.getcurrent()
reactor.callLater(t, g.switch)
g.parent.switch()
def wait_one(d):
print "wait_one(): greenelet:", greenlet.getcurrent()
g = greenlet.getcurrent()
active = True
def callback(result):
if not active:
g.switch(result)
else:
reactor.callLater(0, g.switch, result)
def errback(failure):
if not active:
g.throw(failure)
else:
reactor.callLater(0, g.throw, failure)
d.addCallback(callback)
d.addErrback(errback)
active = False
rc = g.parent.switch()
return rc
@make_async
def inner():
print "inner(): greenelet:", greenlet.getcurrent()
import random, time
interval = random.random()
print "Sleeping for %s seconds..." % interval
sleep(interval)
print "done"
return interval
@make_async
def outer():
print "outer(): greenelet:", greenlet.getcurrent()
print wait_one(inner())
print "Here"
reactor.callLater(0, outer)
reactor.run()
There are 5 main parts: 有五个主要部分:
When I run this code I get this output (Note the error on the last two lines): 运行此代码时,我得到以下输出(请注意最后两行的错误):
outer(): greenelet: <greenlet.greenlet object at 0xb729cc5c>
inner(): greenelet: <greenlet.greenlet object at 0xb729ce3c>
Sleeping for 0.545666723422 seconds...
sleep(): greenelet: <greenlet.greenlet object at 0xb729ce3c>
wait_one(): greenelet: <greenlet.greenlet object at 0xb729cc5c>
done
0.545666723422
Here
Exception twisted.python.failure.Failure: <twisted.python.failure.Failure <class 'greenlet.GreenletExit'>> in <greenlet.greenlet object at 0xb729ce3c> ignored
GreenletExit did not kill <greenlet.greenlet object at 0xb729ce3c>
Doing a bit of research I've found that: 经过一些研究,我发现:
I'm having real trouble debugging this as I can't access the GreenletExit
or twisted.python.failure.Failure
exceptions to get their stack traces. 我在调试它时遇到了麻烦,因为我无法访问
GreenletExit
或twisted.python.failure.Failure
异常以获取其堆栈跟踪。
Does anyone have any ideas what I'm doing wrong, or how I get debug the exceptions that are being thrown? 有谁知道我在做什么错,或者我如何调试正在抛出的异常?
One other data point: If I hack wait_one() to just return immediately (and not to register anything on the deferred it is passed), the errors go away. 另一个数据点:如果我砍下wait_one()以便立即返回(并且不对延迟传递的任何内容进行注册),则错误会消失。 :-/
: - /
Rewrite your error callback in wait_one
like this: 像这样在
wait_one
重写错误回调:
def errback(failure):
## new code
if g.dead:
return
##
if not active:
g.throw(failure)
else:
reactor.callLater(0, g.throw, failure)
If greenlet is dead (finished running), there is no point throwing exceptions in it. 如果greenlet已死(运行结束),则没有任何异常抛出。
mguijarr's answer fixed the problem, but I wanted to write up how I got into this situation. mguijarr的答案解决了该问题,但我想写下我如何陷入这种情况。
I have three greenlets: 我有三个Greenlet:
When the sleep finishes the {main} switches to {inner} which switches to {outer}. 睡眠完成后,{main}切换到{inner},后者切换到{outer}。 Outer then returns and raises GreenletExit in {inner}.
然后,外层返回并在{inner}中引发GreenletExit。 This propogates back to twisted.
这传播回扭曲。 It sees an exception being raised from callback(), and so invokes errback().
它看到从callback()引发了异常,因此调用了errback()。 This tries to throw the exception into {outer} (which has already exited), and I hit the error.
这试图将异常抛出到{outer}中(已经退出),我遇到了错误。
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