imaplib2：imap.gmail.com處理程序BYE響應：系統錯誤

Question

我正在翻新一個python腳本，檢查IMAP是否有新電子郵件，如果有新郵件則發送推送通知。 問題是每隔幾個小時我就會崩潰。 起初我無法理解發生了什么，但后來我發現M.debug = 4給了我一個很好的輸出，但我仍然無法理解導致問題的原因。 我已經將我的腳本和調試輸出從正常行為發布到崩潰，希望在python中有更好理解的人可以告訴我發生了什么以及如何解決它。

編輯：

我按照以下答案中的建議編輯了我的代碼：

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

或這個：

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

但是在一段不確定的時間之后我仍然會遇到崩潰，而且異常永遠不會被抓住。 print("Disconnected. Trying again.")永遠不會執行。

代碼：

    #!/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()

...... ......

  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

...... ......

有時我得到這個：

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

那是因為異常被拋出在另一個線程和另一個沒有被except塊保護的地方。 只需查看回溯 - 您將看到它在threading.py內啟動（並且那里沒有異常處理）。 繼續通過dosync和getUnseen方法 - 再次，沒有異常處理。

這就解釋了為什么你的try / except塊無效 - 那是因為你明確要求在另一個線程中執行該代碼。 還有待解釋的是，為什么你首先得到例外。 一個原因可能是您正在達到通常與IDLE命令相關聯的超時 - 有關詳細信息，請參閱RFC 2177 （這是一個簡短的讀取），它將告訴您，您應該每29分鍾打破一次空閑。 另一種可能性是gmail根本不喜歡你 - 也許他們不喜歡維持連接時間太長的客戶端。 不過，我沒有數據來支持這種猜測。

但最重要的問題仍然存在 - 你為什么要使用線程呢？ 正如有人誰已實施和IMAP客戶端從頭（順便說一句，它在Python很多年前開始），我完全確信線程不需要有效談IMAP。 在您的特定用例中，您似乎只是為IDLE命令運行一個線程，同時花費主線程的時間進行無休止的wait 。 這本身就是我不理解的東西，但也許你有一些重要的原因 - 也許你真的需要將一些IMAP處理卸載到另一個線程。 但是，在這種情況下，請考慮將任何與IMAP相關的活動移動到該線程 - 因為現在，您的一個線程正在執行初始SELECT和一些數據獲取，並且僅在此之后它將IMAP連接轉移到IDLE另一個線程。 那只是邪惡的。

對於線程的基本需求 - 一個對我有用的架構正在利用IMAP協議的異步性質。 我不確定它與imaplib2庫有多好，也許它不支持真正的異步IMAP處理。 在這種情況下，我強烈考慮只是在一種無聊的阻塞同步方式中使用IMAP，其中每個操作都真正等待命令的完成。 是的，其中一些會運行很長時間 - 如果您在等待IDLE在29分鍾后完成時絕對需要執行一些活動， 那么將IMAP處理推遲到另一個可能是個好主意線。 但是你應該非常肯定這是你在走這條路之前真正需要的。

Answer 2

我從頭開始構建相同的應用程序並收到完全相同的錯誤（ BYE響應異常）。

如何在Thread-4中捕獲異常

這是通過包裝解決的

self.M.idle(callback=callback)

try except然后在某處保存異常（例如在Idler的屬性中）。

這個保存的異常會在主線程中持續掃描（即每秒鍾睡眠和喚醒），如果存在，則在主線程中引發以便正確處理（即重新創建的imap連接，如imaplib2中所示）圖書館）。

如何避免來自服務器的BYE響應

為什么會發生這種情況？ 我的推測是，當連接被不正確地關閉時（例如，使用kill信號，這樣就不會進行清理），服務器之前不會從連接接收到NOOP信號，並決定關閉該通道。 但現在是新節目收到“關閉頻道”信號。

為什么我推測這個？ 一旦我實現了BYE imaplib2.abort異常捕獲並殺死捕獲信號（ SIGTERM等）， imaplib2.abort異常就完全停止了。

---

注意：您還可以在我的github中找到這兩種解決方案的確切實現： https ： //www.github.com/Elijas/email-notifier

Answer 3

從您的跟蹤中，它看起來遠程端發送了一個未經請求的BYE命令，因為它想要出於某種原因關閉連接。

您可能必須使腳本更加健壯以處理連接失敗和BYE命令。

例如，您應該將頂級更改為循環：

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

此外，您需要更新回調（）以查看它的參數。 如果IDLE返回錯誤，因為您異步使用它，它將向callback（）報告錯誤。 您需要在那里處理異常。 （注意它不會在回調中引發錯誤，只是在參數中返回錯誤。

來自imaplib2s文檔：

If 'callback' is provided then the command is asynchronous, so after
the command is queued for transmission, the call returns immediately
with the tuple (None, None).
The result will be posted by invoking "callback" with one arg, a tuple:
callback((result, cb_arg, None))
or, if there was a problem:
callback((None, cb_arg, (exception class, reason)))

這意味着你的回調需要查看它的參數：

            def callback(args):
                result, arg, exc = args
                if result is None:
                    print("There was an error during IDLE:", str(exc))
                    self.error = exc
                    self.event.set()
                else:
                    self.needsync = True
                    self.event.set()

現在，您可以檢查您的惰輪線程中是否存在錯誤。 然后在你坐的主線程中，每次60秒，你可以設置某種標志來指示你是否已經斷開連接。