runtime: decrement default cpu amount in nr_jobs (#10841)

vlib/runtime/runtime.c.v

@@ -1,15 +0,0 @@
-// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
-// Use of this source code is governed by an MIT license
-// that can be found in the LICENSE file.
-
-module runtime
-
-//$if linux {
-fn C.sysconf(name int) i64
-
-//}
-
-//$if windows {
-fn C.GetCurrentProcessorNumber() u32
-
-//}

vlib/runtime/runtime.v

@@ -11,12 +11,15 @@ import os
 // then `nr_jobs` will return that number instead.
 // This is useful for runtime tweaking of e.g. threaded or concurrent code.
 pub fn nr_jobs() int {
-	mut cpus := nr_cpus()
+	mut cpus := nr_cpus() - 1
 	// allow for overrides, for example using `VJOBS=32 ./v test .`
 	vjobs := os.getenv('VJOBS').int()
 	if vjobs > 0 {
 		cpus = vjobs
 	}
+	if cpus == 0 {
+		return 1
+	}
 	return cpus
 }
 

vlib/runtime/runtime_darwin.c.v

@@ -1 +0,0 @@
-module runtime

vlib/runtime/runtime_linux.c.v

@@ -1 +0,0 @@
-module runtime

vlib/runtime/runtime_nix.c.v

@@ -1,14 +1,10 @@
 module runtime
 
+fn C.sysconf(name int) i64
+
 // nr_cpus returns the number of virtual CPU cores found on the system.
 pub fn nr_cpus() int {
-	$if linux {
-		return int(C.sysconf(C._SC_NPROCESSORS_ONLN))
-	}
-	$if macos {
-		return int(C.sysconf(C._SC_NPROCESSORS_ONLN))
-	}
-	$if solaris {
+	$if linux || macos || solaris {
 		return int(C.sysconf(C._SC_NPROCESSORS_ONLN))
 	}
 	return 1