How to make SMTPHandler not block

Question

I installed a local SMTP server and used logging.handlers.SMTPHandler to log an exception using this code:

import logging
import logging.handlers
import time
gm = logging.handlers.SMTPHandler(("localhost", 25), '[email protected]', ['[email protected]'], 'Hello Exception!',)
gm.setLevel(logging.ERROR)
logger.addHandler(gm)
t0 = time.clock()
try:
    1/0
except:
    logger.exception('testest')
print time.clock()-t0

It took more than 1sec to complete, blocking the python script for this whole time. How come? How can I make it not block the script?

Answer 1

Here's the implementation I'm using, which I based on this Gmail adapted SMTPHandler.
I took the part that sends to SMTP and placed it in a different thread.

import logging.handlers
import smtplib
from threading import Thread

def smtp_at_your_own_leasure(mailhost, port, username, password, fromaddr, toaddrs, msg):
    smtp = smtplib.SMTP(mailhost, port)
    if username:
        smtp.ehlo() # for tls add this line
        smtp.starttls() # for tls add this line
        smtp.ehlo() # for tls add this line
        smtp.login(username, password)
    smtp.sendmail(fromaddr, toaddrs, msg)
    smtp.quit()

class ThreadedTlsSMTPHandler(logging.handlers.SMTPHandler):
    def emit(self, record):
        try:
            import string # for tls add this line
            try:
                from email.utils import formatdate
            except ImportError:
                formatdate = self.date_time
            port = self.mailport
            if not port:
                port = smtplib.SMTP_PORT
            msg = self.format(record)
            msg = "From: %s\r\nTo: %s\r\nSubject: %s\r\nDate: %s\r\n\r\n%s" % (
                            self.fromaddr,
                            string.join(self.toaddrs, ","),
                            self.getSubject(record),
                            formatdate(), msg)
            thread = Thread(target=smtp_at_your_own_leasure, args=(self.mailhost, port, self.username, self.password, self.fromaddr, self.toaddrs, msg))
            thread.start()
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)

Usage example:

logger = logging.getLogger()

gm = ThreadedTlsSMTPHandler(("smtp.gmail.com", 587), 'bugs@my_company.com', ['admin@my_company.com'], 'Error found!', ('[email protected]', 'top_secret_gmail_password'))
gm.setLevel(logging.ERROR)

logger.addHandler(gm)

try:
    1/0
except:
    logger.exception('FFFFFFFFFFFFFFFFFFFFFFFUUUUUUUUUUUUUUUUUUUUUU-')