[Python-Dev] Inherance of file descriptor and handles on Windows (PEP 446) (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Fri Jul 26 23:24:32 CEST 2013

On Fri, 26 Jul 2013 22:17:47 +0200 Victor Stinner <victor.stinner at gmail.com> wrote:

2013/7/26 Antoine Pitrou <solipsis at pitrou.net>: >> The main drawback is the additionnal syscalls: on some platforms, 2 >> additional syscalls are need to make a file descriptor non-inheritable >> for each creation of file descriptor. According to my benchmark on the >> implementation of the PEP 433: the overhead of making a file >> descriptor non-inheritable is between 1% and 3% (7.8 µs => 7.9 or 8.0 >> µs) on Linux 3.6. > > 1% and 3% of what? > You're telling us there's a 0.1µs overhead. It's positively tiny.

Copy-paste of the link: """ On Linux, setting the close-on-flag has a low overhead on performances. Results of benchcloexec.py on Linux 3.6: - close-on-flag not set: 7.8 us - OCLOEXEC: 1% slower (7.9 us) - ioctl(): 3% slower (8.0 us) - fcntl(): 3% slower (8.0 us) """

You aren't answering my question: slower than what? Benchmarking is useless if you aren't telling us what exactly you are benchmarking.

The overhead is between 0.1 and 0.2 µs (100 and 200 ns) according to my micro-benchmark.

That's what I figured out (see above). It's tiny.

Antoine.

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