Garbage collection not working correctly in Python 2.3

[pythonmeister]

BPO	1405
Nosy	@gvanrossum, @tiran

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2007-11-10.18:23:40.735>
created_at = <Date 2007-11-08.16:31:30.586>
labels = ['interpreter-core', 'invalid', 'performance']
title = 'Garbage collection not working correctly in Python 2.3'
updated_at = <Date 2007-11-10.18:23:40.734>
user = 'https://bugs.python.org/pythonmeister'

bugs.python.org fields:

activity = <Date 2007-11-10.18:23:40.734>
actor = 'gvanrossum'
assignee = 'none'
closed = True
closed_date = <Date 2007-11-10.18:23:40.735>
closer = 'gvanrossum'
components = ['Interpreter Core']
creation = <Date 2007-11-08.16:31:30.586>
creator = 'pythonmeister'
dependencies = []
files = []
hgrepos = []
issue_num = 1405
keywords = []
message_count = 7.0
messages = ['57256', '57263', '57316', '57317', '57319', '57351', '57352']
nosy_count = 4.0
nosy_names = ['gvanrossum', 'christian.heimes', 'pythonmeister', '_doublep']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue1405'
versions = ['Python 2.5', 'Python 2.3']

[pythonmeister]

when running this script:
aList = []
for i in xrange(5E5):
aList += [[]]
for j in xrange(10):
aList[-1].append([])
del aList

It does not give back the memory

even a

import gc
gc.collect()

afterwards does not do it.

In Python 2.5 the memory is freed again correctly, at least under Windows.

The problem came up, because I was parsing a CSV file of 50 MB which
resulted in memory usage of more than 500 MB.

[tiran]

I'm sorry but Python 2.3 is long gone. Its maintenance cycle has ended
over a year ago.Nobody is going to fix an outdated version when the new
versions of Python are working fine. Can you update to a new version of
Python?

[pythonmeister]

No, I can't.
As many Front Arena Developers on the 1.6/2.0/2.1/2.2 can't.
Python 2.4 will be in Front Arena 4.0.
Lightyears away from here.
Same behaviour seen under Solaris 10 / Python 2.5.1

[doublep]

See if gc.set_threshold (0, 0, 0) helps.

[gvanrossum]

How do you know the memory isn't given back? It may be available for
reallocation within Python, just not given back to the operating system.
That's not necessarily a leak or a bug; that could just be heap
fragmentation. There's nothing you can do about it.

[doublep]

Looks like the memory _is_ freed. As Guido said, "It may be available
for reallocation within Python, just not given back to the operating
system". I suggest closing this as invalid.

paul@gonzo:~$ python
Python 2.3.5 (#2, Oct 16 2006, 19:19:48)
[GCC 3.3.5 (Debian 1:3.3.5-13)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import gc
>>> len ([object for object in gc.get_objects () if isinstance (object,
list)])
25
>>> aList = []
>>> for i in xrange(5E5):
...     aList += [[]]
...     for j in xrange(10):
...         aList[-1].append([]
...
...
KeyboardInterrupt
>>>         aList[-1].append([]
KeyboardInterrupt
>>>
paul@gonzo:~/emacs$ python
Python 2.3.5 (#2, Oct 16 2006, 19:19:48)
[GCC 3.3.5 (Debian 1:3.3.5-13)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import gc
>>> len ([object for object in gc.get_objects () if isinstance (object,
list)])
25
>>> aList = []
>>> for i in xrange(5E5):
...     aList += [[]]
...     for j in xrange(10):
...         aList[-1].append([])
...
__main__:1: DeprecationWarning: integer argument expected, got float
>>> del aList
>>> len ([object for object in gc.get_objects () if isinstance (object,
list)])
25

[doublep]

Meh, copied too much. Disregard first part, second shows it.