Bug 1082557: Use a persistent connection to the SMTP server for improved performance

Bugzilla.pm

@@ -659,13 +659,16 @@ sub memcached {
 # Per-process cleanup. Note that this is a plain subroutine, not a method,
 # so we don't have $class available.
 sub _cleanup {
-    my $main   = Bugzilla->request_cache->{dbh_main};
-    my $shadow = Bugzilla->request_cache->{dbh_shadow};
+    my $cache = Bugzilla->request_cache;
+    my $main = $cache->{dbh_main};
+    my $shadow = $cache->{dbh_shadow};
     foreach my $dbh ($main, $shadow) {
         next if !$dbh;
         $dbh->bz_rollback_transaction() if $dbh->bz_in_transaction;
         $dbh->disconnect;
     }
+    my $smtp = $cache->{smtp};
+    $smtp->disconnect if $smtp;
     clear_request_cache();
 
     # These are both set by CGI.pm but need to be undone so that

Bugzilla/Mailer.pm

@@ -25,7 +25,7 @@ use Encode qw(encode);
 use Encode::MIME::Header;
 use Email::MIME;
 use Email::Sender::Simple qw(sendmail);
-use Email::Sender::Transport::SMTP;
+use Email::Sender::Transport::SMTP::Persistent;
 use Bugzilla::Sender::Transport::Sendmail;
 
 sub MessageToMTA {
@@ -127,7 +127,8 @@ sub MessageToMTA {
     }
 
     if ($method eq "SMTP") {
-        $transport = Email::Sender::Transport::SMTP->new({
+        $transport = Bugzilla->request_cache->{smtp} //=
+          Email::Sender::Transport::SMTP::Persistent->new({
             host  => Bugzilla->params->{'smtpserver'},
             sasl_username => Bugzilla->params->{'smtp_username'},
             sasl_password => Bugzilla->params->{'smtp_password'},