[PATCH] nntp: reduce timers for weakening

[Eric Wong <e@80x24.org>]

Danga::Socket timers are not cheap, so avoid creating up
to 3 timers per-newsgroup by batching resource weakening.
This lets us reduce resource consumption for scheduing
additional resource consumption reduction :)
---
 lib/PublicInbox/NNTP.pm      | 19 ++++++++++++++++++-
 lib/PublicInbox/NewsGroup.pm | 30 ++++++------------------------
 2 files changed, 24 insertions(+), 25 deletions(-)

diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index c715e8f..e143d15 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -38,6 +38,8 @@ my %DISABLED; # = map { $_ => 1 } qw(xover list_overview_fmt newnews xhdr);
 my $EXPMAP; # fd -> [ idle_time, $self ]
 my $EXPTIMER;
 our $EXPTIME = 180; # 3 minutes
+my $WEAKEN = {}; # string(nntpd) -> nntpd
+my $WEAKTIMER;
 
 sub update_idle_time ($) {
 	my ($self) = @_;
@@ -46,6 +48,16 @@ sub update_idle_time ($) {
 	defined $tmp and $EXPMAP->{$tmp} = [ now(), $self ];
 }
 
+# reduce FD pressure by closing some "git cat-file --batch" processes
+# and unused FDs for msgmap and Xapian indices
+sub weaken_groups () {
+	$WEAKTIMER = undef;
+	foreach my $nntpd (values %$WEAKEN) {
+		$_->weaken_all foreach (@{$nntpd->{grouplist}});
+	}
+	$WEAKEN = {};
+}
+
 sub expire_old () {
 	my $now = now();
 	my $exp = $EXPTIME;
@@ -69,11 +81,15 @@ sub expire_old () {
 		$next -= $now;
 		$next = 0 if $next < 0;
 		$EXPTIMER = Danga::Socket->AddTimer($next, *expire_old);
+		weaken_groups();
 	} else {
 		$EXPTIMER = undef;
-		# noop to kick outselves out of the loop so descriptors
+		# noop to kick outselves out of the loop ASAP so descriptors
 		# really get closed
 		Danga::Socket->AddTimer(0, sub {});
+
+		# grace period for reaping resources
+		$WEAKTIMER ||= Danga::Socket->AddTimer(30, *weaken_groups);
 	}
 }
 
@@ -87,6 +103,7 @@ sub new ($$$) {
 	$self->{rbuf} = '';
 	$self->watch_read(1);
 	update_idle_time($self);
+	$WEAKEN->{"$nntpd"} = $nntpd;
 	$EXPTIMER ||= Danga::Socket->AddTimer($EXPTIME, *expire_old);
 	$self;
 }
diff --git a/lib/PublicInbox/NewsGroup.pm b/lib/PublicInbox/NewsGroup.pm
index b20180e..adac919 100644
--- a/lib/PublicInbox/NewsGroup.pm
+++ b/lib/PublicInbox/NewsGroup.pm
@@ -24,20 +24,14 @@ sub new {
 	$self;
 }
 
-sub defer_weaken {
-	my ($self, $field) = @_;
-	Danga::Socket->AddTimer(30, sub { weaken($self->{$field}) });
+sub weaken_all {
+	my ($self) = @_;
+	weaken($self->{$_}) foreach qw(gcf mm search);
 }
 
 sub gcf {
 	my ($self) = @_;
-	$self->{gcf} ||= eval {
-		my $gcf = PublicInbox::Git->new($self->{git_dir});
-
-		# git repos may be repacked and old packs unlinked
-		defer_weaken($self, 'gcf');
-		$gcf;
-	};
+	$self->{gcf} ||= eval { PublicInbox::Git->new($self->{git_dir}) };
 }
 
 sub usable {
@@ -50,24 +44,12 @@ sub usable {
 
 sub mm {
 	my ($self) = @_;
-	$self->{mm} ||= eval {
-		my $mm = PublicInbox::Msgmap->new($self->{git_dir});
-
-		# may be needed if we run low on handles
-		defer_weaken($self, 'mm');
-		$mm;
-	};
+	$self->{mm} ||= eval { PublicInbox::Msgmap->new($self->{git_dir}) };
 }
 
 sub search {
 	my ($self) = @_;
-	$self->{search} ||= eval {
-		my $search = PublicInbox::Search->new($self->{git_dir});
-
-		# may be needed if we run low on handles
-		defer_weaken($self, 'search');
-		$search;
-	};
+	$self->{search} ||= eval { PublicInbox::Search->new($self->{git_dir}) };
 }
 
 sub description {
-- 
EW