On Fri, Jun 12, 2009 at 9:06 PM, Christian Heimes wrote:

How about a nice 'n shiny context wrapper for the pipe:

I'll do this! Thank you for the suggestion! BTW, as this is a good way of avoiding the FD leakage, should this context wrapper for pipe() be in the stdlib? Regards, -- . Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

On 14Jun2009 16:42, Mark Seaborn wrote: | I use a convenience function like this, so that GC takes care of the FDs: | | def make_pipe(): | read_fd, write_fd = os.pipe() | return os.fdopen(read_fd, "r"), os.fdopen(write_fd, "w") Not guarrenteed to be timely. The try/except at least closes things as control passes out of the relevant scope. I don't think all pythons do immediate ref-counted GC. But it's very neat! -- Cameron Simpson DoD#743 http://www.cskk.ezoshosting.com/cs/ Trust the computer industry to shorten Year 2000 to Y2K. It was this thinking that caused the problem in the first place. - Mark Ovens

Steven D'Aprano wrote:

On Tue, 16 Jun 2009 01:20:53 pm Cameron Simpson wrote:

...

I don't think all pythons do immediate ref-counted GC.

Jython and IronPython don't. I don't know about PyPy, CLPython, Unladen Swallow, etc.

PyPy doesn't, Unladen Swallow won't. Michael -- http://www.ironpythoninaction.com/

Cameron Simpson wrote:

On 14Jun2009 16:42, Mark Seaborn wrote: | I use a convenience function like this, so that GC takes care of the FDs: | | def make_pipe(): | read_fd, write_fd = os.pipe() | return os.fdopen(read_fd, "r"), os.fdopen(write_fd, "w")

Not guarrenteed to be timely. The try/except at least closes things as control passes out of the relevant scope. I don't think all pythons do immediate ref-counted GC.

Yep. I don't mind closing FDs explicitly when it's easy to do so in a try..finally, but it's not always simple. There are two different problems with non-prompt closing of FDs: * Whether an FD has been closed is sometimes externally observable. e.g. Pipes and sockets notify the other end of the connection. Open file and directory FDs prevent filesystems from being unmounted. * FDs use up space in the process's FD table. The second problem could be dealt with by running the GC when we get EMFILE, or before any calls that allocate FDs when the FD table is almost full, just as the GC runs when we "run out" of memory. I wonder if this proposal could help: 'GC & The "Expensive Object" Problem' http://www.eros-os.org/pipermail/e-lang/1999-May/002590.html Mark