drop GNU nproc(1) support in favor of getconf(1)

`getconf NPROCESSORS_ONLN' will succeed on GNU/Linux systems
anyways; and the non-underscore-prefixed invocation works fine
on all BSD flavors tested.

Thus the `nproc' and `gnproc' attempts will never be reached.
The only downside is we lose the ability to account for CPU
affinity, but that's probably not an issue since CPU affinity
(AFAIK) isn't a commonly-used feature.

1 files changed, 4 insertions, 7 deletions

diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index 39021f42..fa084795 100644
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -464,16 +464,13 @@ sub detect_nproc () {
         my $n = $NPROCESSORS_ONLN{$^O};
         return POSIX::sysconf($n) if defined $n;
 
-        # getconf(1) is POSIX, but *NPROCESSORS* vars are not
+        # getconf(1) is POSIX, but *NPROCESSORS* vars are not even if
+        # glibc, {Free,Net,Open}BSD all support them.
         for (qw(_NPROCESSORS_ONLN NPROCESSORS_ONLN)) {
                 `getconf $_ 2>/dev/null` =~ /^(\d+)$/ and return $1;
         }
-        for my $nproc (qw(nproc gnproc)) { # GNU coreutils nproc
-                `$nproc 2>/dev/null` =~ /^(\d+)$/ and return $1;
-        }
-
-        # should we bother with `sysctl hw.ncpu`?  Those only give
-        # us total processor count, not online processor count.
+        # note: GNU nproc(1) checks CPU affinity, which is nice but
+        # isn't remotely portable
         undef
 }