calling cmake from meson is much slower

When using meson from master instead of 0.55.3, meson build --wipe becomes much slower.

On a small/medium size project with multiple subprojects, around 100 targets and a few external commands:

0.55.3

windows : 5.3s linux : 3.3s

master

windows : 13s linux : 4.7s

I’m particularly concerned with the windows evolution.

Running with cProfile I get this top offender

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
      436   10.685    0.025   10.685    0.025 {method 'acquire' of '_thread.lock' objects}

while on 0.55.3

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
      596    4.284    0.007    4.284    0.007 {method 'acquire' of '_thread.lock' objects}

and pyinstrument shows me that nearly all this time is spent calling cmake (which I use to acquire external dependencies).

A git bisect led me to find this comes from 7e58f33376119b53e01616139ad9354ce9cfe003. Notifying @mensinda

[mensinda]

For reference, I have opened https://discourse.cmake.org/t/skipping-cmake-compiler-checks/2079 to figure out a proper soultion.

[Sahnvour]

@mensinda Tested your suggestion, it’s faster at ~7s with no generator instead of ~10s (my first measurement at 13s was a bit high, maybe cold filesystem or something).