Bugs item #1314519, was opened at 2005-10-06 05:56
Message generated for change (Comment added) made by vsajip
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Category: Python Library
Group: Python 2.4
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Wai Yip Tung (tungwaiyip)
Assigned to: Vinay Sajip (vsajip)
Summary: logging run into deadlock in some error handling situation
Initial Comment:
I've a daemon that pipe stdout and stderr into logging
in order to capture everything it does. It works fine.
However if there is an error throw inside logging, the
error is sent to stderr that got redirect into logging
again. Its seems some lock is not reentrant and it
causes deadlock.
>>> import logging,sys
>>> # a quick and dirty log file object
... class LogFileObj(object):
... def __init__(self,log):
... self.log = log
... def write(self,str):
... self.log.warn(str)
...
>>> # create a logger for stderr
... log = logging.getLogger()
>>>
>>> # for the purpose of showing this bug, output to a
StreamHandler based on stdout
... handler = logging.StreamHandler(sys.stdout)
>>> handler.setFormatter(logging.Formatter('%(asctime)s
%(message)s'))
>>> log.addHandler(handler)
>>>
>>> # redirect stderr to a logger
... sys.stderr = LogFileObj(log)
>>>
>>> # it works!
... print >>sys.stderr, 'hello world'
2005-10-05 22:52:32,391 hello world
2005-10-05 22:52:32,391
>>>
>>> # now put sys.stderr aside
... # use the logger as usual
... log.warn('hello world')
2005-10-05 22:52:32,401 hello world
>>>
>>> # this one has an error in the number of arguments
... log.warn('hello world %s', 1, 2)
When the last statement is ran, it goes into a deadlock.
It seems this can be workaround by using
threading.RLock instead of thread's lock.
>>> # workaround the deadlock by using RLock
... import threading
>>> handler.lock = threading.RLock()
>>> log.warn('hello world %s', 1, 2)
2005-10-05 22:47:46,390 Traceback (most recent call last):
2005-10-05 22:47:46,400 File
"C:\Python24\lib\logging\__init__.py", line 706, in emit
2005-10-05 22:47:46,400 msg = self.format(record)
2005-10-05 22:47:46,400 File
"C:\Python24\lib\logging\__init__.py", line 592, in format
2005-10-05 22:47:46,400 return fmt.format(record)
2005-10-05 22:47:46,400 File
"C:\Python24\lib\logging\__init__.py", line 382, in format
2005-10-05 22:47:46,400 record.message =
record.getMessage()
2005-10-05 22:47:46,400 File
"C:\Python24\lib\logging\__init__.py", line 253, in
getMessage
2005-10-05 22:47:46,400 msg = msg % self.args
2005-10-05 22:47:46,400 TypeError: not all arguments
converted during string formatting
I'm not too familiar with the implementation of
logging. Please keep me posted whether this is a
legitimate workaround.
----------------------------------------------------------------------
>Comment By: Vinay Sajip (vsajip)
Date: 2005-10-06 08:37
Message:
Logged In: YES
user_id=308438
I've just looked into it, and the change has already been
made in CVS (Version 1.27, dated 31/03/2005). The change
should be in Python 2.4.2 final.
Marking as closed.
----------------------------------------------------------------------
Comment By: Vinay Sajip (vsajip)
Date: 2005-10-06 07:53
Message:
Logged In: YES
user_id=308438
Yes, the problem is there and the proposed solution seems
fine. Also note that if you set logging.raiseExceptions to
0, then exceptions during emitting are silently ignored
rather than raised.
I will change thread.allocate_lock() -> threading.RLock()
and check into CVS soon, then mark this as closed.
----------------------------------------------------------------------
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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1314519&group_id=5470
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