mutate.py: cores from OMAPHOTO_CPUS, 32 by default

scripts/mutate.py

@@ -23,13 +23,15 @@ if not os.path.isfile(os.path.join(repo, 'CMakeLists.txt')):
     sys.exit('run mutate.py from the repository root')
 original = open(args.path).read()
 targets = [t for t in args.targets.split(',') if t]
+# Cores for docker and the build, shared by parallel workers.
+cpus = os.environ.get('OMAPHOTO_CPUS', '32')
 
 
 def docker(command):
     uid, gid = os.getuid(), os.getgid()
     runtime = '/run/user/%d' % uid
     done = subprocess.run(
-        ['docker', 'run', '--rm', '--init', '--cpus=32', '-u', '%d:%d' % (uid, gid), '-e', 'HOME=/tmp', '-e', 'QT_QPA_PLATFORM=offscreen',
+        ['docker', 'run', '--rm', '--init', '--cpus=' + cpus, '-u', '%d:%d' % (uid, gid), '-e', 'HOME=/tmp', '-e', 'QT_QPA_PLATFORM=offscreen',
          '--tmpfs', '%s:uid=%d,gid=%d,mode=0700' % (runtime, uid, gid), '-e', 'XDG_RUNTIME_DIR=' + runtime,
          '-v', '%s:%s' % (repo, repo), '-w', repo, 'omaphoto-dev', 'timeout', '600', 'sh', '-c', command],
         capture_output=True, text=True)
@@ -38,7 +40,7 @@ def docker(command):
 
 def build():
     wanted = ' --target ' + ' '.join(targets) if targets else ''
-    return docker('cmake -S . -B build -G Ninja -DOMAPHOTO_WERROR=ON >/dev/null && cmake --build build -j32' + wanted)
+    return docker('cmake -S . -B build -G Ninja -DOMAPHOTO_WERROR=ON >/dev/null && cmake --build build -j' + cpus + wanted)
 
 
 def test():