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Issue File: Python26\Lib\logging\__init__.py
class FileHandler(StreamHandler):
 """
 A handler class which writes formatted logging records to disk files.
 """
 def __init__(self, filename, mode='a', encoding=None, delay=0):
 """
 Open the specified file and use it as the stream for logging.
 """
 #keep the absolute path, otherwise derived classes which use this
 #may come a cropper when the current directory changes
 if codecs is None:
 encoding = None
 self.baseFilename = os.path.abspath(filename)
 self.mode = mode
 self.encoding = encoding
 if delay:
 #We don't open the stream, but we still need to call the
 #Handler constructor to set level, formatter, lock etc.
 Handler.__init__(self) ## 1. here will insert instance into logging._handlerList
 self.stream = None
 else:
 StreamHandler.__init__(self, self._open())
 def close(self):
 """
 Closes the stream.
 """
 if self.stream: ## 2. when delay=1, here should call Handler.close(self), or the instance still store in logging._handlerList, lead to leak (instance's owner's __del__ will not be called).
 self.flush()
 if hasattr(self.stream, "close"):
 self.stream.close()
 StreamHandler.close(self)
 self.stream = None
------------------------------------------------
leak demo:
import logging
import time
def using_handler():
 filename = "test.log"
 handler = logging.FileHandler(filename, mode="w", delay=1)
 handler.close()
def test():
 while True:
 using_handler()
 time.sleep(.01)
if __name__ == "__main__":
 test()
If you run this script, and then view the Task Manager for this process's handlers, it is growing forever.
------------------------------------
Solution: very easy
Fix the method FileHandler.close:
 def close(self):
 """
 Closes the stream.
 """
 if self.stream:
 self.flush()
 if hasattr(self.stream, "close"):
 self.stream.close()
 StreamHandler.close(self)
 self.stream = None
 else: 
 Handler.close(self) 
regards
DDGG

If you run this script, and then view the Task Manager for this process's handles, it is growing forever.
handlers -> handles. this leak handle is Handler.lock object, because the instance was not be garbage-collected.

New changeset bbb227b96c45 by Vinay Sajip in branch '2.7':
Issue #19523: Closed FileHandler leak which occurred when delay was set.
http://hg.python.org/cpython/rev/bbb227b96c45
New changeset 058810fe1b98 by Vinay Sajip in branch '3.3':
Issue #19523: Closed FileHandler leak which occurred when delay was set.
http://hg.python.org/cpython/rev/058810fe1b98
New changeset a3640822c3e6 by Vinay Sajip in branch 'default':
Closes #19523: Merged fix from 3.3.
http://hg.python.org/cpython/rev/a3640822c3e6