git-http-backend: use qspawn to limit running processes

Having an excessive amount of git-pack-objects processes is
dangerous to the health of the server.  Queue up process spawning
for long-running responses and serve them sequentially, instead.

1 files changed, 15 insertions, 23 deletions

diff --git a/lib/PublicInbox/GitHTTPBackend.pm b/lib/PublicInbox/GitHTTPBackend.pm
index ded56b33..9464cb49 100644
--- a/lib/PublicInbox/GitHTTPBackend.pm
+++ b/lib/PublicInbox/GitHTTPBackend.pm
@@ -8,9 +8,9 @@ use strict;
 use warnings;
 use Fcntl qw(:seek);
 use IO::File;
-use PublicInbox::Spawn qw(spawn);
 use HTTP::Date qw(time2str);
 use HTTP::Status qw(status_message);
+use PublicInbox::Qspawn;
 
 # n.b. serving "description" and "cloneurl" should be innocuous enough to
 # not cause problems.  serving "config" might...
@@ -167,11 +167,6 @@ sub serve_smart {
         unless (defined $fd && $fd >= 0) {
                 $in = input_to_file($env) or return r(500);
         }
-        my ($rpipe, $wpipe);
-        unless (pipe($rpipe, $wpipe)) {
-                err($env, "error creating pipe: $! - going static");
-                return;
-        }
         my %env = %ENV;
         # GIT_COMMITTER_NAME, GIT_COMMITTER_EMAIL
         # may be set in the server-process and are passed as-is
@@ -187,20 +182,13 @@ sub serve_smart {
         my $git_dir = $git->{git_dir};
         $env{GIT_HTTP_EXPORT_ALL} = '1';
         $env{PATH_TRANSLATED} = "$git_dir/$path";
-        my %rdr = ( 0 => fileno($in), 1 => fileno($wpipe) );
-        my $pid = spawn([qw(git http-backend)], \%env, \%rdr);
-        unless (defined $pid) {
-                err($env, "error spawning: $! - going static");
-                return;
-        }
-        $wpipe = $in = undef;
-        my $fh;
+        my %rdr = ( 0 => fileno($in) );
+        my $x = PublicInbox::Qspawn->new([qw(git http-backend)], \%env, \%rdr);
+        my ($fh, $rpipe);
         my $end = sub {
                 $rpipe = undef;
-                my $e = $pid == waitpid($pid, 0) ?
-                        $? : "PID:$pid still running?";
-                if ($e) {
-                        err($env, "git http-backend ($git_dir): $e");
+                if (my $err = $x->finish) {
+                        err($env, "git http-backend ($git_dir): $err");
                         drop_client($env);
                 }
                 $fh->close if $fh; # async-only
@@ -248,11 +236,15 @@ sub serve_smart {
                 # holding the input here is a waste of FDs and memory
                 $env->{'psgi.input'} = undef;
 
-                if ($async) {
-                        $async = $async->($rpipe, $cb, $end);
-                } else { # generic PSGI
-                        $cb->() while $rd_hdr;
-                }
+                $x->start(sub { # may run later, much later...
+                        ($rpipe) = @_;
+                        $in = undef;
+                        if ($async) {
+                                $async = $async->($rpipe, $cb, $end);
+                        } else { # generic PSGI
+                                $cb->() while $rd_hdr;
+                        }
+                });
         };
 }