When using tornado multi process deploy, the log handler TimedRotatingFileHandler will cause exception when the log file split. Because one of the process rename the log file and create a new log file, then the log file descriptor changed. So, we make every process has its own log file, and name it with the process id.

tornado_multiprocess_log

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright 2012 Ethan Zhang<http://github.com/Ethan-Zhang> 
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the                                                    
# License for the specific language governing permissions and limitations
# under the License.


import signal                                                                                                                 
import os                                                                                                                     
import logging                                                                                                                
import logging.handlers                                                                                                       

import tornado
import tornado.netutil                                                                                                        
import tornado.process                                                                                                        
from tornado.ioloop import IOLoop                                                                                             
from tornado.httpserver import HTTPServer                                                                                     

def handle_request(request):
    message = "You requested %s\n" % request.uri                                                                              
    request.write("HTTP/1.1 200 OK\r\nContent-Length: %d\r\n\r\n%s" % (                                                       
                               len(message), message))
    request.finish()

def kill_server(sig, frame):

    IOLoop.instance().stop()


def main():

    signal.signal(signal.SIGPIPE, signal.SIG_IGN);
    signal.signal(signal.SIGINT, kill_server)
    signal.signal(signal.SIGQUIT, kill_server)
    signal.signal(signal.SIGTERM, kill_server)
    signal.signal(signal.SIGHUP, kill_server)

    sockets = tornado.netutil.bind_sockets(9204)
    task_id = tornado.process.fork_processes(2)

    logger = logging.getLogger()
    logger.setLevel(logging.DEBUG)
    log_file = 'tornadolog.log.%d' % (task_id)
    timelog = timelog = logging.handlers.TimedRotatingFileHandler(log_file,
                                                                'midnight', 
                                                                1, 0)
    logger.addHandler(timelog)

    server = HTTPServer(handle_request)
    server.add_sockets(sockets)

    logger.info('Server Starting...')

    IOLoop.instance().start()
    server.stop()
    IOLoop.instance().stop()

if __name__ == '__main__':
    main()