Python:代码崩溃 - 重新启动脚本

Question

imap_host = 'imap.gmail.com'
mail = imaplib.IMAP4_SSL(imap_host)
mail.login(user,passw)
mail.select("inbox") # connect to inbox.

while True:
    try:
        result, data = mail.uid('search', None, 'UNSEEN')
        uid_list = data[0].split()
        print len(uid_list), 'Unseen emails.'
        time.sleep(60)
    except KeyboardInterrupt:
        print 'Quitting'
        return 


Traceback (most recent call last):
  File "gmail_new2.py", line 12, in <module>
    mail.select("inbox") # connect to inbox
  File "/usr/lib/python2.6/imaplib.py", line 642, in select
    typ, dat = self._simple_command(name, mailbox)
  File "/usr/lib/python2.6/imaplib.py", line 1060, in _simple_command
    return self._command_complete(name, self._command(name, *args))
  File "/usr/lib/python2.6/imaplib.py", line 890, in _command_complete
    raise self.abort('command: %s => %s' % (name, val))
imaplib.abort: command: SELECT => socket error: EOF

该代码连接到 Gmail 并返回未读电子邮件。它工作正常，但有时会返回该错误并崩溃。

当代码崩溃时，如何纠正错误或重新启动代码？

Answer 1

如果失败的语句是 mail.select，您可以将其包装在 try/except block 中并实现重试策略。

如果问题与服务可用性有关，您可能需要尝试exponential backoff strategy使用指数增长的计时器来安排重试尝试。

一个简单的例子如下:

selected = False
retry_timer = 1
while not selected:
    try:
        mail.select('inbox')
        selected = True
    except imaplib.abort:
        time.sleep(retry_timer)
        retry_timer *= 2