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

Victor Stinner victor.stinner at gmail.com
Sat Jul 27 00🔞40 CEST 2013

2013/7/26 Antoine Pitrou <solipsis at pitrou.net>:

On Fri, 26 Jul 2013 22:17:47 +0200

""" 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?

Ah, you didn't understand the labels. bench_cloexec.py runs a benchmark on os.open(path, os.O_RDONLY, cloexec=False) and os.open(path, os.O_RDONLY, cloexec=True) with different implementation of making the file descriptor non-inheritable.

close-on-flag not set: 7.8 us => C code: open(path, O_RDONLY)

O_CLOEXEC: 1% slower (7.9 us) => C code: open(path, O_RDONLY|CLOEXEC) => 1% slower than open(path, O_RDONLY)

ioctl(): 3% slower (8.0 us) => C code: fd=open(path, O_RDONLY); ioctl(fd, FIOCLEX, 0) => 3% slower than open(path, O_RDONLY)

fcntl(): 3% slower (8.0 us) => C code: fd=open(path, O_RDONLY); flags = fcntl(fd, F_GETFD); fcntl(fd, F_SETFD, flags | FD_CLOEXEC) => 3% slower than open(path, O_RDONLY)

Victor

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