socketserver.TCPSocket leaks socket to garbage collector if server_bind() fails

[vadmium]

BPO	22435
Nosy	@pitrou, @vstinner, @vadmium
Files	socketserver_bind_leak.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 = None
closed_at = <Date 2015-02-27.02:50:39.865>
created_at = <Date 2014-09-18.00:25:22.433>
labels = ['library', 'performance']
title = 'socketserver.TCPSocket leaks socket to garbage collector if server_bind() fails'
updated_at = <Date 2015-02-27.02:50:39.864>
user = 'https://github.com/vadmium'

bugs.python.org fields:

activity = <Date 2015-02-27.02:50:39.864>
actor = 'berker.peksag'
assignee = 'none'
closed = True
closed_date = <Date 2015-02-27.02:50:39.865>
closer = 'berker.peksag'
components = ['Library (Lib)']
creation = <Date 2014-09-18.00:25:22.433>
creator = 'martin.panter'
dependencies = []
files = ['36665']
hgrepos = []
issue_num = 22435
keywords = ['patch']
message_count = 6.0
messages = ['227017', '227126', '227234', '229256', '229259', '236723']
nosy_count = 5.0
nosy_names = ['pitrou', 'vstinner', 'neologix', 'python-dev', 'martin.panter']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue22435'
versions = ['Python 3.4', 'Python 3.5']

[vadmium]

Bind method may easily fail on Unix if there is no permission to bind to a privileged port:

>>> try: TCPServer(("", 80), ...)
... except Exception as err: err
... 
PermissionError(13, 'Permission denied')
>>> gc.collect()
__main__:1: ResourceWarning: unclosed <socket.socket fd=3, family=AddressFamily.AF_INET, type=SocketType.SOCK_STREAM, proto=0, laddr=('0.0.0.0', 0)>
0

This problem is inherited by HTTPServer and WSGIServer. My current workaround includes this code in a BaseServer fixup mixin, invoking server_close() if __init__() fails:

class Server(BaseServer, Context):
    def __init__(self, ...):
        try:
            super().__init__((host, port), RequestHandlerClass)
        except:  # Workaround for socketserver.TCPServer leaking socket
            self.close()
            raise
    
    def close(self):
        return self.server_close()

[neologix]

Patch attached.
The test wouldn't result in FD exhaustion on CPython because of the reference counting, but should still trigger RessourceWarning.

[pitrou]

Patch looks of to me.

[python-dev]

New changeset 437002018d2d by Charles-François Natali in branch '2.7':
Issue bpo-22435: Fix a file descriptor leak when SocketServer bind fails.
https://hg.python.org/cpython/rev/437002018d2d

[python-dev]

New changeset 9c8016af2ed8 by Charles-François Natali in branch '3.4':
Issue bpo-22435: Fix a file descriptor leak when SocketServer bind fails.
https://hg.python.org/cpython/rev/9c8016af2ed8

New changeset 3bd0f2516445 by Charles-François Natali in branch 'default':
Issue bpo-22435: Fix a file descriptor leak when SocketServer bind fails.
https://hg.python.org/cpython/rev/3bd0f2516445

[vadmium]

This is fixed in 3.4.3. I think it can be closed.