我正在编写一个简单的服务器程序。它们将是新鲜代码中不可避免的拼写错误和其他错误,通常python解释器将打印ValueError / AttributeError回溯并退出。回溯可以指向错误的确切位置。但是,在扭曲的框架下,不会打印这些错误。如下例所示:
from twisted.internet import reactor, protocol, task
#from twisted.internet.defer import setDebugging
#setDebugging(True)
class MyProtocol(protocol.Protocol):
def dataReceived(self, data):
try:
set_position(int(data))
except ValueError:
pass
def connectionMade(self):
self.factory.clientConnectionMade(self)
def connectionLost(self, reason):
self.factory.clientConnectionLost(self)
class MyFactory(protocol.Factory):
protocol = MyProtocol
def __init__(self):
self.clients = []
self.lc = task.LoopingCall(self.announce)
self.lc.start(1)
def announce(self):
pos = A_GREAT_TYPO_HERE()
for client in self.clients:
client.transport.write("Posiiton is {0}\n".format(pos).encode('utf-8'))
def clientConnectionMade(self, client):
self.clients.append(client)
def clientConnectionLost(self, client):
self.clients.remove(client)
def get_position():
return position[0]
def set_position(pos):
position[0] = pos
def main():
global position
position = [0]
myfactory = MyFactory()
reactor.listenTCP(5362, myfactory)
reactor.run()
if __name__ == "__main__":
main()
MyFactory.announce中的 A_GREAT_TYPO_HERE()
应为get_position()
。但这是一个错字。
当服务器运行时,终端只输出
Unhandled error in Deferred:
,没有别的。即使我启用延迟调试(取消注释第2和第3行),终端输出:
Unhandled error in Deferred:
(debug: C: Deferred was created:
C: File "nodes/test.py", line 48, in <module>
C: main()
C: File "nodes/test.py", line 43, in main
C: myfactory = MyFactory()
C: File "nodes/test.py", line 21, in __init__
C: self.lc.start(1)
C: File "/home/sgsdxzy/anaconda3/lib/python3.6/site-packages/twisted/internet/task.py", line 189, in start
C: deferred = self._deferred = defer.Deferred()
I: First Invoker was:
I: File "nodes/test.py", line 48, in <module>
I: main()
I: File "nodes/test.py", line 43, in main
I: myfactory = MyFactory()
I: File "nodes/test.py", line 21, in __init__
I: self.lc.start(1)
I: File "/home/sgsdxzy/anaconda3/lib/python3.6/site-packages/twisted/internet/task.py", line 194, in start
I: self()
I: File "/home/sgsdxzy/anaconda3/lib/python3.6/site-packages/twisted/internet/task.py", line 241, in __call__
I: d.addErrback(eb)
I: File "/home/sgsdxzy/anaconda3/lib/python3.6/site-packages/twisted/internet/defer.py", line 332, in addErrback
I: errbackKeywords=kw)
I: File "/home/sgsdxzy/anaconda3/lib/python3.6/site-packages/twisted/internet/defer.py", line 310, in addCallbacks
I: self._runCallbacks()
I: File "/home/sgsdxzy/anaconda3/lib/python3.6/site-packages/twisted/internet/defer.py", line 653, in _runCallbacks
I: current.result = callback(current.result, *args, **kw)
I: File "/home/sgsdxzy/anaconda3/lib/python3.6/site-packages/twisted/internet/task.py", line 236, in eb
I: d.errback(failure)
)
它将错误指向self.lc.start(1)
,但不是A_GREAT_TYPO_HERE()
。如何调试我的程序,以便回溯可以指向实际错误?
答案 0 :(得分:0)
&#34; C&#34;和&#34;我&#34;您看到的行是由于您启用了延迟调试。 &#34; C&#34; lines为您提供创建Deferred的堆栈。 &#34;我&#34; line为你提供了Deferred被调用的堆栈&#34; (调用了callback
或errback
方法。)
看来,这些都不是你正在寻找的。如果你想看到与被驱逐的Failure
相关联的堆栈,最直接的解决方案是确保Failure
被记录(并且你有一个日志观察者,这样你就可以实际上看到了日志事件。
您应该将其添加到main
:
from sys import stdout
from twisted.logger import globalLogBeginner, textFileLogObserver
globalLogBeginner.beginLoggingTo([textFileLogObserver(stdout)])
这会将日志流作为文本引导到stdout。最有可能获得您想要的信息。但是,为了确保安全,您还需要显式记录故障,而不是依赖垃圾收集器为您执行此操作。所以你也想改变:
self.lc.start(1)
要:
# Module scope
from twisted.logger import Logger
logger = Logger()
...
# in __init__
d = self.lc.start(1)
d.addErrback(lambda f: logger.failure("Loop thing problem", f))
(另外,您可能需要考虑从__init__
中取出此代码并将其放入startFactory
;也可以考虑不使用全局反应器,而是将其作为参数传递。)
这将为您提供如下输出:
2017-04-25T06:53:14-0400 [__main__.MyFactory#critical] Foo
Traceback (most recent call last):
File "debugging2.py", line 52, in main
myfactory = MyFactory()
File "debugging2.py", line 28, in __init__
d = self.lc.start(1)
File "/tmp/debugging/local/lib/python2.7/site-packages/twisted/internet/task.py", line 194, in start
self()
File "/tmp/debugging/local/lib/python2.7/site-packages/twisted/internet/task.py", line 239, in __call__
d = defer.maybeDeferred(self.f, *self.a, **self.kw)
--- <exception caught here> ---
File "/tmp/debugging/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 150, in maybeDeferred
result = f(*args, **kw)
File "debugging2.py", line 32, in announce
pos = A_GREAT_TYPO_HERE()
exceptions.NameError: global name 'A_GREAT_TYPO_HERE' is not defined