Re: [libvirt] [PATCH v4 00/26] scripts: convert most perl scripts to python

On Wed, Oct 09, 2019 at 12:37:15PM +0100, Daniel P. Berrangé wrote: > Note that the check-spacing.py script is significantly > slower in Python than in Perl. After researching this > it appears there is nothing that can be done. The Perl > regex engine is simply much better optimized than the > Python one. I'm afraid immutability of strings does not help either. I tried speeding it up a bit by running the regexes conditionally, e.g.: + if '"' in data: + data = quotedstringprog.sub('"XXX"', data) That got it down from 0m6.368s to 0m3.802s (compared to perl's 1.5s), but even before that change, I don't consider the Python version of this one script to be more readable. Note that perl's optimizations aren't perfect either - merely moving all the checks into a subroutine resulted in a significant slowdown. > As previously discussed we need to loook > at uncrustify or clang-format or some other tool to > validate whitespace formatting. This is ongoing. We > can either accept the slow down in the short term or > keep the Perl version in the short term. > Just to set the expectations, running clang-format on all the C files took me ~40 s. Not sure how much that can be efficiently parallelized or if meson could be convinced to start clang-format as the first thing for the 'check' target, even before starting to compile anything.