From b5c8031c8f202c8140ee69c901c0e719a244aa77 Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@gnu.kitenet.net>
Date: Fri, 10 Jul 2009 10:51:46 -0400
Subject: [PATCH] use sysconf to determine number of processors

---
 parallel.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/parallel.c b/parallel.c
index 0895c13..8045e22 100644
--- a/parallel.c
+++ b/parallel.c
@@ -30,6 +30,7 @@
 #include <sys/select.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <unistd.h>
 
 void usage() {
 	printf("parallel [OPTIONS] command -- arguments: for each argument, "
@@ -121,9 +122,13 @@ int main(int argc, char **argv) {
 		}
 	}
 
-	if (maxjobs < 0 && maxload < 0) {
-		maxjobs = 1; /* XXX: Maybe we should try to autodetect
-				number of CPUs? */
+	if (maxjobs < 0) {
+#ifdef _SC_NPROCESSORS_ONLN
+		maxjobs = sysconf(_SC_NPROCESSORS_ONLN);
+#else
+#warning Cannot autodetect number of CPUS on this system: _SC_NPROCESSORS_ONLN not defined.
+		maxjobs = 1;
+#endif
 	}
 
 	while (optind < argc) {
-- 
2.39.5