imaplib2：imap.gmail.com网站处理程序BYE响应：系统

Question

我正在更新一个python脚本，它检查IMAP中是否有新的电子邮件，如果有新的电子邮件，则发送一个推送通知。问题是每隔几个小时我就有一次车祸。一开始我真的不明白到底发生了什么，但后来我发现M.debug = 4给了我一个很好的输出，但我仍然不明白是什么导致了这个问题。我已经发布了我的脚本和从正常行为到崩溃的调试输出，希望对python有更好理解的人可以告诉我发生了什么，以及如何修复它。在

编辑：

我已经按照答案中的建议编辑了我的代码：

while True:
    try:
      [call function that does all your logic]
    except imaplib2.IMAP4.abort:
      print("Disconnected.  Trying again.")

或者这个：

^{pr2}$

但在一段不确定的时间后，我还是会崩溃，而且这个例外永远不会被发现。print("Disconnected. Trying again.")永远不会执行。在

代码：

    #!/usr/local/bin/python2.7
    print "Content-type: text/html\r\n\r\n";

    import socket, ssl, json, struct, re
    import imaplib2, time
    from threading import *

    # enter gmail login details here
    USER="username@gmail.com"
    PASSWORD="password"
    # enter device token here
    deviceToken = 'my device token x x x x x'
    deviceToken = deviceToken.replace(' ','').decode('hex')
    currentBadgeNum = -1

    def getUnseen():
        (resp, data) = M.status("INBOX", '(UNSEEN)')
        print data
        return int(re.findall("UNSEEN (\d)*\)", data[0])[0])    

    def sendPushNotification(badgeNum):
        global currentBadgeNum, deviceToken
        if badgeNum != currentBadgeNum:
            currentBadgeNum = badgeNum
            thePayLoad = {
                 'aps': {
                      'alert':'Hello world!',
                      'sound':'',
                      'badge': badgeNum,
                      },
                 'test_data': { 'foo': 'bar' },
                 }
            theCertfile = 'certif.pem'
            theHost = ('gateway.push.apple.com', 2195)

            data = json.dumps(thePayLoad)
            theFormat = '!BH32sH%ds' % len(data)
            theNotification = struct.pack(theFormat, 0, 32, deviceToken, len(data), data)

            ssl_sock = ssl.wrap_socket(socket.socket(socket.AF_INET, socket.SOCK_STREAM), certfile=theCertfile)
            ssl_sock.connect(theHost)
            ssl_sock.write(theNotification)
            ssl_sock.close()
            print "Sent Push alert."

    # This is the threading object that does all the waiting on 
    # the event
    class Idler(object):
        def __init__(self, conn):
            self.thread = Thread(target=self.idle)
            self.M = conn
            self.event = Event()

        def start(self):
            self.thread.start()

        def stop(self):
            # This is a neat trick to make thread end. Took me a 
            # while to figure that one out!
            self.event.set()

        def join(self):
            self.thread.join()

        def idle(self):
            # Starting an unending loop here
            while True:
                # This is part of the trick to make the loop stop 
                # when the stop() command is given
                if self.event.isSet():
                    return
                self.needsync = False
                # A callback method that gets called when a new 
                # email arrives. Very basic, but that's good.
                def callback(args):
                    if not self.event.isSet():
                        self.needsync = True
                        self.event.set()
                # Do the actual idle call. This returns immediately, 
                # since it's asynchronous.
                self.M.idle(callback=callback)
                # This waits until the event is set. The event is 
                # set by the callback, when the server 'answers' 
                # the idle call and the callback function gets 
                # called.
                self.event.wait()
                # Because the function sets the needsync variable,
                # this helps escape the loop without doing 
                # anything if the stop() is called. Kinda neat 
                # solution.
                if self.needsync:
                    self.event.clear()
                    self.dosync()

        # The method that gets called when a new email arrives. 
        # Replace it with something better.
        def dosync(self):
            print "Got an event!"
            numUnseen = getUnseen()
            sendPushNotification(numUnseen)

    # Had to do this stuff in a try-finally, since some testing 
    # went a little wrong.....
while True:
    try:
        # Set the following two lines to your creds and server
        M = imaplib2.IMAP4_SSL("imap.gmail.com")
        M.login(USER, PASSWORD)
        M.debug = 4
        # We need to get out of the AUTH state, so we just select 
        # the INBOX.
        M.select("INBOX")
        numUnseen = getUnseen()
        sendPushNotification(numUnseen)

        typ, data = M.fetch(1, '(RFC822)')
        raw_email = data[0][1]

        import email
        email_message = email.message_from_string(raw_email)
        print email_message['Subject']

        #print M.status("INBOX", '(UNSEEN)')
        # Start the Idler thread
        idler = Idler(M)
        idler.start()


        # Sleep forever, one minute at a time
        while True:
            time.sleep(60)
    except imaplib2.IMAP4.abort:
      print("Disconnected.  Trying again.")   
    finally:
        # Clean up.
        #idler.stop() #Commented out to see the real error
        #idler.join() #Commented out to see the real error
        #M.close()    #Commented out to see the real error
        # This is important!
        M.logout()

。。。 ... ... 在

  43:54.43 imap.gmail.com handler _request_pop(continuation, (True, 'idling')) = CHPJ127
  43:54.43 imap.gmail.com handler None:CHPJ127.ready.set
  43:54.43 Thread-4 continuation => True, idling
  43:54.43 Thread-4 server IDLE started, timeout in 1740.00 secs
  43:54.43 Thread-4 state_change_pending.release
  57:13.60 imap.gmail.com reader < * BYE System error\r\n
  57:13.63 imap.gmail.com handler server IDLE finished
  57:13.63 imap.gmail.com handler BYE response: System error
  57:13.63 imap.gmail.com writer > DONE\r\n
  **57:13.63 imap.gmail.com handler terminating: 'connection terminated'**
  57:13.63 imap.gmail.com writer finished
  57:13.63 imap.gmail.com handler last 20 log messages:
  51:49.77 Thread-4 [sync] IDLE ()
  20:50.18 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  20:50.51 Thread-4 [sync] IDLE ()
  49:50.79 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  49:51.02 Thread-4 [sync] IDLE ()
  18:51.33 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  18:51.49 Thread-4 [sync] IDLE ()
  47:51.80 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  47:51.96 Thread-4 [sync] IDLE ()
  16:52.26 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  16:52.63 Thread-4 [sync] IDLE ()
  45:53.08 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  45:53.24 Thread-4 [sync] IDLE ()
  14:53.54 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  14:53.69 Thread-4 [sync] IDLE ()
  43:53.96 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  43:54.17 Thread-4 [sync] IDLE ()
  57:13.63 imap.gmail.com handler BYE response: System error
  57:13.63 imap.gmail.com handler terminating: 'connection terminated'
  57:13.63 imap.gmail.com writer finished
Got an event!
  57:13.63 imap.gmail.com handler state_change_free.set
  57:13.63 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  57:13.63 imap.gmail.com handler finished
  57:13.63 Thread-4 state_change_pending.acquire
  57:13.63 Thread-4 state_change_pending.release
Exception in thread Thread-4:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/local/lib/python2.7/threading.py", line 504, in run
    self.__target(*self.__args, **self.__kwargs)
  File "shaserver.py", line 111, in idle
    self.dosync()
  File "shaserver.py", line 117, in dosync
    numUnseen = getUnseen()
  File "shaserver.py", line 35, in getUnseen
    (resp, data) = M.status("INBOX", '(UNSEEN)')
  File "/home/boombe/lib/python2.7/imaplib2/imaplib2.py", line 1121, in status
    return self._simple_command(name, mailbox, names, **kw)
  File "/home/boombe/lib/python2.7/imaplib2/imaplib2.py", line 1607, in _simple_command
    return self._command_complete(self._command(name, *args), kw)
  File "/home/boombe/lib/python2.7/imaplib2/imaplib2.py", line 1295, in _command
    self._check_bye()
  File "/home/boombe/lib/python2.7/imaplib2/imaplib2.py", line 1229, in _check_bye
    raise self.abort(bye[-1])
abort: System error

  57:13.70 imap.gmail.com reader finished

。。。 ... ... 在

有时我会发现：

03:09.29 Thread-4 [sync] IDLE ()
  05:53.25 imap.gmail.com reader socket error: <type 'exceptions.IOError'> - Error Hang up
  05:53.25 imap.gmail.com reader finished
  05:53.26 imap.gmail.com handler terminating: "socket error: <type 'exceptions.IOError'> - Error Hang up"
  05:53.26 imap.gmail.com handler last 20 log messages:
  07:07.66 Thread-4 [sync] IDLE ()
  36:07.78 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  36:07.83 Thread-4 [async] SEARCH ('ALL',)
  36:07.88 Thread-4 [async] FETCH ('1', '(RFC822.HEADER)')
  36:08.09 Thread-4 [sync] IDLE ()
  05:08.19 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  05:08.25 Thread-4 [async] SEARCH ('ALL',)
  05:08.42 Thread-4 [async] FETCH ('1', '(RFC822.HEADER)')
  05:08.48 Thread-4 [sync] IDLE ()
  34:08.58 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  34:08.68 Thread-4 [async] SEARCH ('ALL',)
  34:08.79 Thread-4 [async] FETCH ('1', '(RFC822.HEADER)')
  34:08.94 Thread-4 [sync] IDLE ()
  03:09.05 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  03:09.16 Thread-4 [async] SEARCH ('ALL',)
  03:09.21 Thread-4 [async] FETCH ('1', '(RFC822.HEADER)')
  03:09.29 Thread-4 [sync] IDLE ()
  05:53.25 imap.gmail.com reader socket error: <type 'exceptions.IOError'> - Error Hang up
  05:53.25 imap.gmail.com reader finished
  05:53.26 imap.gmail.com handler terminating: "socket error: <type 'exceptions.IOError'> - Error Hang up"
  05:53.26 imap.gmail.com writer finished
Got an event!
  05:53.26 Thread-4 [async] STATUS ('INBOX', '(UNSEEN)')
  05:53.26 Thread-4 state_change_pending.acquire
  05:53.26 Thread-4 server IDLE finished
  05:53.26 Thread-4 state_change_pending.release
  05:53.26 Thread-4 _get_untagged_response(READ-ONLY) => ['']
  05:53.26 imap.gmail.com handler state_change_free.set
  05:53.26 imap.gmail.com handler finished
Exception in thread Thread-4:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/local/lib/python2.7/threading.py", line 504, in run
    self.__target(*self.__args, **self.__kwargs)
  File "shaserver.py", line 229, in idle
    self.dosync()
  File "shaserver.py", line 235, in dosync
    numUnseen = getUnseen()
  File "shaserver.py", line 150, in getUnseen
    (resp, data) = M.status("INBOX", '(UNSEEN)')
  File "/home/boombe/lib/python2.7/imaplib2/imaplib2.py", line 1121, in status
    return self._simple_command(name, mailbox, names, **kw)
  File "/home/boombe/lib/python2.7/imaplib2/imaplib2.py", line 1607, in _simple_command
    return self._command_complete(self._command(name, *args), kw)
  File "/home/boombe/lib/python2.7/imaplib2/imaplib2.py", line 1305, in _command
    raise self.abort('connection closed')
abort: connection closed

Answer 1

这是因为异常被抛出到另一个线程和另一个不受except块保护的地方。只需看看回溯跟踪，就会发现它是从threading.py开始的（其中没有异常处理）。再次通过dosync和getUnseen方法继续，没有异常处理。

这就解释了为什么你的try/except块无效，这是因为你明确要求在另一个线程中执行该代码。还有待解释的是为什么你会首先得到例外。一个原因可能是您遇到了与IDLE命令相关联的超时，有关详细信息，请参见RFC 2177（这是一个简短的阅读），它将告诉您应该每隔29分钟中断一次空闲。另一种可能是gmail根本不喜欢你，也许他们不想维持那些连接时间太长的客户。不过，我没有推测数据。

但最重要的问题仍然是为什么要使用线程？作为一个从零开始实现和IMAP client的人（顺便说一句，它是在很多年前用Python实现的），我完全确信线程是而不是来高效地讨论IMAP的。在您的特定用例中，您似乎只为IDLE命令运行一个线程，而将主线程的时间花在无休止的wait中。这本身是我不明白的，但也许你有一些重要的原因，也许你真的需要将一些IMAP处理卸载到另一个线程。但是，在这种情况下，请考虑将任何与IMAP相关的活动移动到该线程，因为现在，您的一个线程正在执行初始的SELECT和一些数据获取，并且只有在这之后，它才将IMAP连接传输到IDLE的另一个线程。那真是邪恶。

对于线程化的基本需求，一个对我来说很好的架构就是利用IMAP协议的异步特性。我不确定它在imaplib2库中能发挥多好，也许它不支持真正的异步IMAP处理。在这种情况下，我强烈考虑只在borin中使用IMAP，阻塞同步方式，在这种方式下，每个操作都真正等待命令的完成。是的，如果您确实需要在29分钟后执行某个活动（例如等待该活动在29分钟后完成），则其中一些将运行很长时间，然后将IMAP处理推迟到另一个线程可能是个好主意。但你应该非常确定这是你真正需要的，在你走那条路之前。