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Bugs item #1282539, was opened at 2005-09-05 16:12
Message generated for change (Settings changed) made by rhettinger
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Category: Python Library
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Fons Dijkstra (fdij)
>Assigned to: Vinay Sajip (vsajip)
Summary: logging.shutdown() not correct for chained handlers

Initial Comment:
Consider the following code:

import logging
import logging.handlers

if __name__ == "__main__":
fh = logging.handlers.RotatingFileHandler("log.txt")
mh = logging.handlers.MemoryHandler(1024,
logging.ERROR, fh)
logging.getLogger().addHandler(mh)
logging.getLogger().warning("next statement crashes")
logging.shutdown()

which results in a crash due to operating on a closed
file. The reason is that the shutdown flushes and closes
all handlers in undefined order. In above case, first
the 'fh' handlers is flushes and closed then the 'mh'
handler.

The solution is to first flush all handlers times the
number of handlers before closing them. Thus (omitting
error handling):

def shutdown():
for i in range(len(_handlers)):
for h in _handlers.keys():
h.flush()
for h in _handlers.keys():
h.close()


----------------------------------------------------------------------

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Bugs item #1282539, was opened at 2005-09-05 21:12
Message generated for change (Comment added) made by vsajip
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1282539&group_id=5470

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including the initial issue submission, for this request,
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Category: Python Library
Group: Python 2.4
Status: Open
>Resolution: Accepted
Priority: 5
Submitted By: Fons Dijkstra (fdij)
Assigned to: Vinay Sajip (vsajip)
Summary: logging.shutdown() not correct for chained handlers

Initial Comment:
Consider the following code:

import logging
import logging.handlers

if __name__ == "__main__":
fh = logging.handlers.RotatingFileHandler("log.txt")
mh = logging.handlers.MemoryHandler(1024,
logging.ERROR, fh)
logging.getLogger().addHandler(mh)
logging.getLogger().warning("next statement crashes")
logging.shutdown()

which results in a crash due to operating on a closed
file. The reason is that the shutdown flushes and closes
all handlers in undefined order. In above case, first
the 'fh' handlers is flushes and closed then the 'mh'
handler.

The solution is to first flush all handlers times the
number of handlers before closing them. Thus (omitting
error handling):

def shutdown():
for i in range(len(_handlers)):
for h in _handlers.keys():
h.flush()
for h in _handlers.keys():
h.close()


----------------------------------------------------------------------

>Comment By: Vinay Sajip (vsajip)
Date: 2005-09-07 11:12

Message:
Logged In: YES
user_id=308438

There is indeed a problem - thanks for the report. Rather
than your proposed solution, I would rather add another
internal list, _handlerList, which holds the handlers in
*reverse* order of creation. When shutting down, (a copy of)
this list is used for the iteration rather than
_handlers.keys().

I may remove _handlers in the future - I can't remember why
I made it a dict rather than a list.

Will check into CVS soon, then mark this as Fixed.

----------------------------------------------------------------------

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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1282539&group_id=5470
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Bugs item #1282539, was opened at 2005-09-05 21:12
Message generated for change (Comment added) made by vsajip
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1282539&group_id=5470

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: Python Library
Group: Python 2.4
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Fons Dijkstra (fdij)
Assigned to: Vinay Sajip (vsajip)
Summary: logging.shutdown() not correct for chained handlers

Initial Comment:
Consider the following code:

import logging
import logging.handlers

if __name__ == "__main__":
fh = logging.handlers.RotatingFileHandler("log.txt")
mh = logging.handlers.MemoryHandler(1024,
logging.ERROR, fh)
logging.getLogger().addHandler(mh)
logging.getLogger().warning("next statement crashes")
logging.shutdown()

which results in a crash due to operating on a closed
file. The reason is that the shutdown flushes and closes
all handlers in undefined order. In above case, first
the 'fh' handlers is flushes and closed then the 'mh'
handler.

The solution is to first flush all handlers times the
number of handlers before closing them. Thus (omitting
error handling):

def shutdown():
for i in range(len(_handlers)):
for h in _handlers.keys():
h.flush()
for h in _handlers.keys():
h.close()


----------------------------------------------------------------------

>Comment By: Vinay Sajip (vsajip)
Date: 2005-09-19 01:01

Message:
Logged In: YES
user_id=308438

Now checked into CVS.

----------------------------------------------------------------------

Comment By: Vinay Sajip (vsajip)
Date: 2005-09-07 11:12

Message:
Logged In: YES
user_id=308438

There is indeed a problem - thanks for the report. Rather
than your proposed solution, I would rather add another
internal list, _handlerList, which holds the handlers in
*reverse* order of creation. When shutting down, (a copy of)
this list is used for the iteration rather than
_handlers.keys().

I may remove _handlers in the future - I can't remember why
I made it a dict rather than a list.

Will check into CVS soon, then mark this as Fixed.

----------------------------------------------------------------------

You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1282539&group_id=5470
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