python - logging.handler.TimedRotatingFileHandler never rotates the log -

a have script synchronizes time on linux servers( centos 6) , writes offset in log. want make after 10 days current log (ntp.log) copy old (ntp.log-date), not work. script continues write 1 file , not rotating. run cron every 5 minutes. using python version 2.6. set interval in seconds check. doing wrong?

#!/usr/bin/env python import ntplib import logging logging.handlers import timedrotatingfilehandler time import ctime import os import socket  hostname = socket.gethostname() loghandler = timedrotatingfilehandler('/root/ntp/log/ntp.log', when='s', interval=300) logformatter = logging.formatter('%(asctime)s %(message)s', datefmt='%d/%m/%y %h:%m:%s') loghandler.setformatter(logformatter) logger = logging.getlogger('mylogger') logger.addhandler(loghandler) logger.setlevel(logging.info)   c = ntplib.ntpclient() response = c.request('1.rhel.pool.ntp.org') logger.info('| %s time offset | %s' % (hostname, response.offset)) datestr = ctime(response.tx_time) os.system('date -s "%s"' % datestr) 

leaving outside fact algorithm plain incorrect, i'll answer question regarding logging issue.

here's related logging.handlers.timedrotatingfilehandler logic:

def __init__(<...>):     <...>     if self.when == 's':         self.interval = 1 # 1 second     <...>     self.interval = self.interval * interval # multiply units requested     <...>     if os.path.exists(filename):         t = os.stat(filename)[st_mtime]     else:         t = int(time.time())     self.rolloverat = self.computerollover(t)  def computerollover(self, currenttime):     result = currenttime + self.interval     <special logic doesn't apply in case>     return result 

so, rollover time in 's' mode computed file's mtime @ time of script's init. mtime modified each time write file.

thus, rollover done if log after interval seconds since script's start. never case since runs less.

possible fixes:

• make script run long, e.g. infinite loop suggested. if it's run indefinitely, should made daemon
• change rollover moment calculation algorithm
  • this not possible stock logic (the "special logic" in timedrotatingfilehandler.computerollover() applies 'midnight' , 'wn' cases), need replace handler's computerollover()
  • basically, need set rollover time next "reference moment" after current file's mtime.