[ python-Bugs-1497962 ] Leak in tarfile.py

[SourceForge.net]

Bugs item #1497962, was opened at 2006-05-31 08:42
Message generated for change (Comment added) made by jensj
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1497962&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: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Jens Jørgen Mortensen (jensj)
Assigned to: Nobody/Anonymous (nobody)
Summary: Leak in tarfile.py

Initial Comment:
There is a leak when using the tarfile module and the
extractfile method.  Here is a simple example:
 
$ echo "grrr" > x.txt
$ tar cf x.tar x.txt
$ python
Python 2.4.2 (#2, Sep 30 2005, 21:19:01)
[GCC 4.0.2 20050808 (prerelease) (Ubuntu
4.0.1-4ubuntu8)] on linux2
Type "help", "copyright", "credits" or "license" for
more information.
>>> import gc
>>> import tarfile
>>> tar = tarfile.open('x.tar', 'r')
>>> f = tar.extractfile('x.txt')
>>> f.read()
'grrr\n'
>>> del f
>>> gc.set_debug(gc.DEBUG_LEAK)
>>> print gc.collect()
gc: collectable <ExFileObject 0xb73d4acc>
gc: collectable <dict 0xb73dcf0c>
gc: collectable <instancemethod 0xb7d2daf4>
3
>>> print gc.garbage
[<tarfile.ExFileObject object at 0xb73d4acc>, {'name':
'x.txt', 'read': <bound method ExFileObject._readnormal
of <tarfile.ExFileObject object at 0xb73d4acc>>, 'pos':
0L, 'fileobj': <open file 'x.tar', mode 'rb' at
0xb73e67b8>, 'mode': 'r', 'closed': False, 'offset':
512L, 'linebuffer': '', 'size': 5L}, <bound method
ExFileObject._readnormal of <tarfile.ExFileObject
object at 0xb73d4acc>>]
>>>


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

>Comment By: Jens Jørgen Mortensen (jensj)
Date: 2006-06-01 22:08

Message:
Logged In: YES 
user_id=716463

Problem is that the ExfileObject hat an attribute
(self.read) that is a method bound to itself
(self._readsparse or self._readnormal).  One solution is to
add "del self.read" to the close method, but someone might
forget to close the object and still get the leak.  Another
solution is to change the end of __init__ to:

  if tarinfo.issparse():
      self.sparse = tarinfo.sparse
  else:
      self.sparse = None

and add a read method:

  def read(self, size=None):
      if self.sparse is None:
          return self._readnormal(size)
      else:
          return self._readsparse(size)


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

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1497962&group_id=5470