[Python-Dev] closing files and sockets in a timely manner in the stdlib

[Glyph Lefkowitz]

On Oct 30, 2010, at 2:39 PM, Jack Diederich wrote:

> On Fri, Oct 29, 2010 at 8:35 PM, Brett Cannon <brett at python.org> wrote:
>> For those of you who have not noticed, Antoine committed a patch that
>> raises a ResourceWarning under a pydebug build if a file or socket is
>> closed through garbage collection instead of being explicitly closed.
> 
> Just yesterday I discovered /proc/<your PID here>/fd/ which is a list
> of open file descriptors for your PID on *nix and includes all open
> files, pipes, and sockets.  Very handy, I filed some tickets about
> company internal libs that were opening file handles as a side effect
> of import (logging mostly).  I tried to provoke standard python
> imports (non-test) to leave some open handles and came up empty.

That path (and anything below /proc, really) is a list of open file descriptors specifically on Linux, not "*nix".  Also on linux, you can avoid "<your pid here>" by just doing "/proc/self".

A more portable (albeit not standard) path for "what file descriptors do I have open" is /dev/fd/.  This is supported via a symlink to /proc/self on all the Linuxes I've tested on.  There's no portable standard equivalent for not-yourself processes that I'm aware of, though.

See more discussion here: <http://twistedmatrix.com/trac/ticket/4522>.

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