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| author | Rémi Verschelde <rverschelde@gmail.com> | 2022-07-17 01:09:18 +0200 |
|---|---|---|
| committer | Rémi Verschelde <rverschelde@gmail.com> | 2022-07-17 12:38:41 +0200 |
| commit | ea211225754ba3fc1c2afb290bf26bd714125b24 (patch) | |
| tree | 70e500d57719c09f01c97b7cb8c900983e34cd9b /SConstruct | |
| parent | 9dfd120a7e7c6e9b8af581ceac75847f2696e855 (diff) | |
SCons: Default `num_jobs` to max CPUs minus 1 if not specified
This doesn't change the behavior when `--jobs`/`-j` is specified as a
command-line argument or in `SCONSFLAGS`.
The SCons hack used to know if `num_jobs` was set by the user is derived
from the MongoDB setup.
We use `os.cpu_count()` for portability (available since Python 3.4).
With 4 CPUs or less, we use the max. With more than 4 we use max - 1 to
preserve some bandwidth for the user's other programs.
Diffstat (limited to 'SConstruct')
| -rw-r--r-- | SConstruct | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/SConstruct b/SConstruct index 50cb43b218..0eba93e4ff 100644 --- a/SConstruct +++ b/SConstruct @@ -399,6 +399,24 @@ if selected_platform in platform_list: env = env_base.Clone() + # Default num_jobs to local cpu count if not user specified. + # SCons has a peculiarity where user-specified options won't be overridden + # by SetOption, so we can rely on this to know if we should use our default. + initial_num_jobs = env.GetOption("num_jobs") + altered_num_jobs = initial_num_jobs + 1 + env.SetOption("num_jobs", altered_num_jobs) + if env.GetOption("num_jobs") == altered_num_jobs: + cpu_count = os.cpu_count() + if cpu_count is None: + print("Couldn't auto-detect CPU count to configure build parallelism. Specify it with the -j argument.") + else: + safer_cpu_count = cpu_count if cpu_count <= 4 else cpu_count - 1 + print( + "Auto-detected %d CPU cores available for build parallelism. Using %d cores by default. You can override it with the -j argument." + % (cpu_count, safer_cpu_count) + ) + env.SetOption("num_jobs", safer_cpu_count) + if env["compiledb"]: # Generating the compilation DB (`compile_commands.json`) requires SCons 4.0.0 or later. from SCons import __version__ as scons_raw_version |