[issue21679] Prevent extraneous fstat during open()

[Bohuslav "Slavek" Kabrda]

New submission from Bohuslav "Slavek" Kabrda:

Hi,
with Python 3.3/3.4, I noticed that there are lots of syscalls on open() - I noticed 2x fstat, 2x ioctl and 2x lseek. This is not noticable when working with small amounts of files on local filesystem, but if working with files via NSF or if working with huge amounts of files, lots of syscalls cost a lot of time. Therefore I'd like to create patches that would reduce the number of syscalls on open().
I've already managed to create first one (attached), that gets rid of one of the fstat calls (all the information are obtained from one fstat call).
I hope this makes sense and that the patch is acceptable. If not, I'll be happy to work on it to make it better. (This is my first real patch for C part of Python, so I hope I did everything right...)

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components: IO
files: python3-remove-extraneous-fstat-on-file-open.patch
keywords: patch
messages: 219874
nosy: bkabrda
priority: normal
severity: normal
status: open
title: Prevent extraneous fstat during open()
type: resource usage
versions: Python 3.4, Python 3.5
Added file: http://bugs.python.org/file35494/python3-remove-extraneous-fstat-on-file-open.patch

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<http://bugs.python.org/issue21679>
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