Closed files keep their buffer alive

[pitrou]

BPO	15488
Nosy	@jcea, @pitrou, @benjaminp, @meadori, @hynek, @serhiy-storchaka
Files	a16403affccd 53aa92a70127.diff

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

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GitHub fields:

assignee = 'https://github.com/jcea'
closed_at = <Date 2012-10-04.10:38:44.199>
created_at = <Date 2012-07-29.17:56:31.987>
labels = ['library', 'expert-IO', 'performance']
title = 'Closed files keep their buffer alive'
updated_at = <Date 2012-10-04.10:39:22.753>
user = 'https://github.com/pitrou'

bugs.python.org fields:

activity = <Date 2012-10-04.10:39:22.753>
actor = 'jcea'
assignee = 'jcea'
closed = True
closed_date = <Date 2012-10-04.10:38:44.199>
closer = 'python-dev'
components = ['Library (Lib)', 'IO']
creation = <Date 2012-07-29.17:56:31.987>
creator = 'pitrou'
dependencies = []
files = ['26638', '27413']
hgrepos = ['143']
issue_num = 15488
keywords = ['patch']
message_count = 8.0
messages = ['166801', '166804', '167076', '167080', '167081', '167097', '167117', '171931']
nosy_count = 8.0
nosy_names = ['jcea', 'pitrou', 'benjamin.peterson', 'stutzbach', 'meador.inge', 'python-dev', 'hynek', 'serhiy.storchaka']
pr_nums = []
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue15488'
versions = ['Python 3.4']

[pitrou]

>>> f = open("LICENSE", "rb")
>>> sys.getsizeof(f)
4296
>>> f.close()
>>> sys.getsizeof(f)
4296

Instead of waiting for the file object's deallocation, perhaps we should free the buffer when it is closed?

[benjaminp]

Sounds reasonable to me.

[jcea]

I take care of this.

[jcea]

Please, review patch

[meadori]

The test should go in the 'SizeofTest' class and maybe a better test would be a variant of the test already in that class:

    @support.cpython_only
    def test_buffer_freeing(self) :
        bufsize = 4096
        rawio = self.MockRawIO()
        bufio = self.tp(rawio, buffer_size=bufsize)
        size = sys.getsizeof(bufio) - bufsize
        bufio.close()
        self.assertEqual(sys.getsizeof(bufio), size)

Otherwise, LGTM.

[serhiy-storchaka]

Agree with Meador.

[pitrou]

This has to wait for 3.4, since it's an enhancement, not a bug.

[python-dev]

New changeset 4141c36954cd by Jesus Cea in branch 'default':
Closes bpo-15488: Closed files keep their buffer alive
http://hg.python.org/cpython/rev/4141c36954cd