user/dev discussion of public-inbox itself
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From: Eric Wong <e@yhbt.net>
To: meta@public-inbox.org
Subject: [PATCH 9/9] v2writable: more ways to detect online CPU count
Date: Sun,  2 Feb 2020 06:52:22 +0000
Message-ID: <20200202065222.14966-10-e@yhbt.net> (raw)
In-Reply-To: <20200202065222.14966-1-e@yhbt.net>

OpenBSD and FreeBSD support `getconf NPROCESSORS_ONLN` (no
leading underscore).  They may also have GNU nproc installed as
"gnproc".

We may also encounter Linux systems w/o GNU coreutils, but able
to use `getconf _NPROCESSORS_ONLN` (with leading underscore).
---
 lib/PublicInbox/V2Writable.pm | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index 72d8d5af..82843241 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -7,6 +7,7 @@ package PublicInbox::V2Writable;
 use strict;
 use warnings;
 use base qw(PublicInbox::Lock);
+use 5.010_001;
 use PublicInbox::SearchIdxShard;
 use PublicInbox::MIME;
 use PublicInbox::Git;
@@ -32,14 +33,29 @@ my $PACKING_FACTOR = 0.4;
 # to increase Xapian shards
 our $NPROC_MAX_DEFAULT = 4;
 
+sub detect_nproc () {
+	for my $nproc (qw(nproc gnproc)) { # GNU coreutils nproc
+		`$nproc 2>/dev/null` =~ /^(\d+)$/ and return $1;
+	}
+
+	# getconf(1) is POSIX, but *NPROCESSORS* vars are not
+	for (qw(_NPROCESSORS_ONLN NPROCESSORS_ONLN)) {
+		`getconf $_ 2>/dev/null` =~ /^(\d+)$/ and return $1;
+	}
+
+	# should we bother with `sysctl hw.ncpu`?  Those only give
+	# us total processor count, not online processor count.
+	undef
+}
+
 sub nproc_shards ($) {
 	my ($creat_opt) = @_;
 	my $n = $creat_opt->{nproc} if ref($creat_opt) eq 'HASH';
 	$n //= $ENV{NPROC};
 	if (!$n) {
-		chomp($n = `nproc 2>/dev/null`);
-		# assume 2 cores if GNU nproc(1) is not available
-		$n = 2 if !$n;
+		# assume 2 cores if not detectable or zero
+		state $NPROC_DETECTED = detect_nproc() || 2;
+		$n = $NPROC_DETECTED;
 		$n = $NPROC_MAX_DEFAULT if $n > $NPROC_MAX_DEFAULT;
 	}
 

      parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-02  6:52 [PATCH 0/9] convert: more fixes and tests Eric Wong
2020-02-02  6:52 ` [PATCH 1/9] t/multi-mid.t: extra test for -convert highwater mark Eric Wong
2020-02-02  6:52 ` [PATCH 2/9] v2writable: nproc_shards: subtract 1 from given value Eric Wong
2020-02-02  6:52 ` [PATCH 3/9] v2writable: do not clobber {shards} or {parallel} if unset Eric Wong
2020-02-02  6:52 ` [PATCH 4/9] convert: remove unused variables capturing :from Eric Wong
2020-02-02  6:52 ` [PATCH 5/9] searchidxshard: rely on autoflush instead of ->flush Eric Wong
2020-02-02  6:52 ` [PATCH 6/9] convert: shift @ARGV explicitly Eric Wong
2020-02-02  6:52 ` [PATCH 7/9] convert: fix --no-index switch Eric Wong
2020-02-02  6:52 ` [PATCH 8/9] doc: -convert: document switches Eric Wong
2020-02-02  6:52 ` Eric Wong [this message]

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