nntp: reduce timers for weakening

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 :)

1 files changed, 18 insertions, 1 deletions

diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index c715e8f7..e143d15c 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;
 }