logging - python does not release filehandles to logfile

Question

I have an application which has to run a number of simulation runs. I want to setup a logging mechanisme where all logrecords are logged in a general.log, and all logs for a simulation run go to run00001.log, .... For this I have defined a class Run. in the __init__() a new filehandle is added for the runlog.

The problem is that the logfiles for the runs never get released, so after a number of runs the available handles are exhausted and the run crashes.

I've set up some routines to test this as follows

main routine

import Model
try:
    myrun = Model.Run('20130315150340_run_49295')
    ha = raw_input('enter')
    myrun.log.info("some info")
except:
    traceback.print_exc(file=sys.stdout)

ha = raw_input('enter3')

The class Run is defined in module Model as follows

import logging
class Run(object):

    """ Implements the functionality of a single run. """
    def __init__(self, runid):
        self.logdir="."
        self.runid          = runid
        self.logFile        = os.path.join(self.logdir , self.runid + '.log')
        self.log            = logging.getLogger('Run'+self.runid)
        myformatter         = logging.Formatter('%(asctime)s %(name)-12s %(levelname)-8s %(message)s')
        myhandler      = logging.FileHandler(self.logFile)
        myhandler.setLevel(logging.INFO)
        myhandler.setFormatter(myformatter)
        self.log.addHandler(myhandler) 

Then I use the program process explorer to follow the filehandlers. And I see the runlogs appear, but never disappear.

Is there a way I can force this?

Answer 1

You need to call .close() on the filehandler.

When your Run class completes, call:

handlers = self.log.handlers[:]
for handler in handlers:
    handler.close()
    self.log.removeHandler(handler)