问题
I do struggle with the logging a bit. I'd like to roll over the logs after certain period of time and also after reaching certain size.
Rollover after a period of time is made by TimedRotatingFileHandler, and rollover after reaching certain log size is made by RotatingFileHandler.
But the TimedRotatingFileHandler doesn't have the attribute maxBytes and the RotatingFileHandler can not rotate after a certain period of time.
I also tried to add both handlers to logger, but the result was doubled logging.
Do I miss something?
I also looked into source code of logging.handlers. I tried to subclass TimedRotatingFileHandler and override the method shouldRollover() to create a class with capabilities of both:
class EnhancedRotatingFileHandler(logging.handlers.TimedRotatingFileHandler):
def __init__(self, filename, when='h', interval=1, backupCount=0, encoding=None, delay=0, utc=0, maxBytes=0):
""" This is just a combination of TimedRotatingFileHandler and RotatingFileHandler (adds maxBytes to TimedRotatingFileHandler) """
# super(self). #It's old style class, so super doesn't work.
logging.handlers.TimedRotatingFileHandler.__init__(self, filename, when='h', interval=1, backupCount=0, encoding=None, delay=0, utc=0)
self.maxBytes=maxBytes
def shouldRollover(self, record):
"""
Determine if rollover should occur.
Basically, see if the supplied record would cause the file to exceed
the size limit we have.
we are also comparing times
"""
if self.stream is None: # delay was set...
self.stream = self._open()
if self.maxBytes > 0: # are we rolling over?
msg = "%s\n" % self.format(record)
self.stream.seek(0, 2) #due to non-posix-compliant Windows feature
if self.stream.tell() + len(msg) >= self.maxBytes:
return 1
t = int(time.time())
if t >= self.rolloverAt:
return 1
#print "No need to rollover: %d, %d" % (t, self.rolloverAt)
return 0
But like this the log creates one backup and the gets overwritten. Seems like I have to override also method doRollover() which is not so easy.
Any other idea how to create a logger which rolls the file over after certain time and also after certain size reached?
回答1:
So I made a small hack to TimedRotatingFileHandler to be able to do rollover after both, time and size. I had to modify __init__, shouldRollover, doRollover and getFilesToDelete (see below). This is the result, when I set up when='M', interval=2, backupCount=20, maxBytes=1048576:
-rw-r--r-- 1 user group 185164 Jun 10 00:54 sumid.log
-rw-r--r-- 1 user group 1048462 Jun 10 00:48 sumid.log.2011-06-10_00-48.001
-rw-r--r-- 1 user group 1048464 Jun 10 00:48 sumid.log.2011-06-10_00-48.002
-rw-r--r-- 1 user group 1048533 Jun 10 00:49 sumid.log.2011-06-10_00-48.003
-rw-r--r-- 1 user group 1048544 Jun 10 00:50 sumid.log.2011-06-10_00-49.001
-rw-r--r-- 1 user group 574362 Jun 10 00:52 sumid.log.2011-06-10_00-50.001
You can see that first four logs were rolled over after reaching size of 1MB, while the last rollover occurred after two minutes. So far I didn't test deleting of old log files, so it probably doesn't work. The code certainly will not work for backupCount>=1000. I append just three digits at the end of the file name.
This is the modified code:
class EnhancedRotatingFileHandler(logging.handlers.TimedRotatingFileHandler):
def __init__(self, filename, when='h', interval=1, backupCount=0, encoding=None, delay=0, utc=0, maxBytes=0):
""" This is just a combination of TimedRotatingFileHandler and RotatingFileHandler (adds maxBytes to TimedRotatingFileHandler) """
logging.handlers.TimedRotatingFileHandler.__init__(self, filename, when, interval, backupCount, encoding, delay, utc)
self.maxBytes=maxBytes
def shouldRollover(self, record):
"""
Determine if rollover should occur.
Basically, see if the supplied record would cause the file to exceed
the size limit we have.
we are also comparing times
"""
if self.stream is None: # delay was set...
self.stream = self._open()
if self.maxBytes > 0: # are we rolling over?
msg = "%s\n" % self.format(record)
self.stream.seek(0, 2) #due to non-posix-compliant Windows feature
if self.stream.tell() + len(msg) >= self.maxBytes:
return 1
t = int(time.time())
if t >= self.rolloverAt:
return 1
#print "No need to rollover: %d, %d" % (t, self.rolloverAt)
return 0
def doRollover(self):
"""
do a rollover; in this case, a date/time stamp is appended to the filename
when the rollover happens. However, you want the file to be named for the
start of the interval, not the current time. If there is a backup count,
then we have to get a list of matching filenames, sort them and remove
the one with the oldest suffix.
"""
if self.stream:
self.stream.close()
# get the time that this sequence started at and make it a TimeTuple
currentTime = int(time.time())
dstNow = time.localtime(currentTime)[-1]
t = self.rolloverAt - self.interval
if self.utc:
timeTuple = time.gmtime(t)
else:
timeTuple = time.localtime(t)
dstThen = timeTuple[-1]
if dstNow != dstThen:
if dstNow:
addend = 3600
else:
addend = -3600
timeTuple = time.localtime(t + addend)
dfn = self.baseFilename + "." + time.strftime(self.suffix, timeTuple)
if self.backupCount > 0:
cnt=1
dfn2="%s.%03d"%(dfn,cnt)
while os.path.exists(dfn2):
dfn2="%s.%03d"%(dfn,cnt)
cnt+=1
os.rename(self.baseFilename, dfn2)
for s in self.getFilesToDelete():
os.remove(s)
else:
if os.path.exists(dfn):
os.remove(dfn)
os.rename(self.baseFilename, dfn)
#print "%s -> %s" % (self.baseFilename, dfn)
self.mode = 'w'
self.stream = self._open()
newRolloverAt = self.computeRollover(currentTime)
while newRolloverAt <= currentTime:
newRolloverAt = newRolloverAt + self.interval
#If DST changes and midnight or weekly rollover, adjust for this.
if (self.when == 'MIDNIGHT' or self.when.startswith('W')) and not self.utc:
dstAtRollover = time.localtime(newRolloverAt)[-1]
if dstNow != dstAtRollover:
if not dstNow: # DST kicks in before next rollover, so we need to deduct an hour
addend = -3600
else: # DST bows out before next rollover, so we need to add an hour
addend = 3600
newRolloverAt += addend
self.rolloverAt = newRolloverAt
def getFilesToDelete(self):
"""
Determine the files to delete when rolling over.
More specific than the earlier method, which just used glob.glob().
"""
dirName, baseName = os.path.split(self.baseFilename)
fileNames = os.listdir(dirName)
result = []
prefix = baseName + "."
plen = len(prefix)
for fileName in fileNames:
if fileName[:plen] == prefix:
suffix = fileName[plen:-4]
if self.extMatch.match(suffix):
result.append(os.path.join(dirName, fileName))
result.sort()
if len(result) < self.backupCount:
result = []
else:
result = result[:len(result) - self.backupCount]
return result
回答2:
If you really need this functionality, write your own handler based on TimedRotatingFileHandler to primarily use time for rolling over, but incorporate sized-based rollover into the existing logic. You've tried this, but you need to (at a minimum) override both shouldRollover() and doRollover() methods. The first method determines when to roll over, the second does the closing of the current log file, renaming existing files and deleting obsolete files, then opening the new file.
The doRollover() logic may be a little tricky, but certainly doable.
回答3:
Here is what I use:
import logging
class EnhancedRotatingFileHandler(logging.handlers.TimedRotatingFileHandler, logging.handlers.RotatingFileHandler):
'''
cf http://stackoverflow.com/questions/29602352/how-to-mix-logging-handlers-file-timed-and-compress-log-in-the-same-config-f
Spec:
Log files limited in size & date. I.E. when the size or date is overtaken, there is a file rollover
'''
########################################
def __init__(self, filename, mode = 'a', maxBytes = 0, backupCount = 0, encoding = None,
delay = 0, when = 'h', interval = 1, utc = False):
logging.handlers.TimedRotatingFileHandler.__init__(
self, filename, when, interval, backupCount, encoding, delay, utc)
logging.handlers.RotatingFileHandler.__init__(self, filename, mode, maxBytes, backupCount, encoding, delay)
########################################
def computeRollover(self, currentTime):
return logging.handlers.TimedRotatingFileHandler.computeRollover(self, currentTime)
########################################
def getFilesToDelete(self):
return logging.handlers.TimedRotatingFileHandler.getFilesToDelete(self)
########################################
def doRollover(self):
return logging.handlers.TimedRotatingFileHandler.doRollover(self)
########################################
def shouldRollover(self, record):
""" Determine if rollover should occur. """
return (logging.handlers.TimedRotatingFileHandler.shouldRollover(self, record) or logging.handlers.RotatingFileHandler.shouldRollover(self, record))
回答4:
I adapted Julien's code for my usage. Now it rollover after reaching certain log size or after a period of time.
class EnhancedRotatingFileHandler(logging.handlers.TimedRotatingFileHandler, logging.handlers.RotatingFileHandler):
def __init__(self, filename, mode='a', maxBytes=0, backupCount=0, encoding=None,
delay=0, when='h', interval=1, utc=False):
logging.handlers.TimedRotatingFileHandler.__init__(
self, filename=filename, when=when, interval=interval,
backupCount=backupCount, encoding=encoding, delay=delay, utc=utc)
logging.handlers.RotatingFileHandler.__init__(self, filename=filename, mode=mode, maxBytes=maxBytes,
backupCount=backupCount, encoding=encoding, delay=delay)
def computeRollover(self, current_time):
return logging.handlers.TimedRotatingFileHandler.computeRollover(self, current_time)
def doRollover(self):
# get from logging.handlers.TimedRotatingFileHandler.doRollover()
current_time = int(time.time())
dst_now = time.localtime(current_time)[-1]
new_rollover_at = self.computeRollover(current_time)
while new_rollover_at <= current_time:
new_rollover_at = new_rollover_at + self.interval
# If DST changes and midnight or weekly rollover, adjust for this.
if (self.when == 'MIDNIGHT' or self.when.startswith('W')) and not self.utc:
dst_at_rollover = time.localtime(new_rollover_at)[-1]
if dst_now != dst_at_rollover:
if not dst_now: # DST kicks in before next rollover, so we need to deduct an hour
addend = -3600
else: # DST bows out before next rollover, so we need to add an hour
addend = 3600
new_rollover_at += addend
self.rolloverAt = new_rollover_at
return logging.handlers.RotatingFileHandler.doRollover(self)
def shouldRollover(self, record):
return logging.handlers.TimedRotatingFileHandler.shouldRollover(self, record) or logging.handlers.RotatingFileHandler.shouldRollover(self, record)
来源：https://stackoverflow.com/questions/6167587/the-logging-handlers-how-to-rollover-after-time-or-maxbytes