avoid calling waitpid from children in DESTROY

Objects with DESTROY callbacks get propagated to children, so we
must be careful to not invoke waitpid from children on their
sibling processes.  Only parents (and their parents...) can reap
child processes.

1 files changed, 6 insertions, 2 deletions

diff --git a/lib/PublicInbox/Gcf2Client.pm b/lib/PublicInbox/Gcf2Client.pm
index 10820852..54957cf3 100644
--- a/lib/PublicInbox/Gcf2Client.pm
+++ b/lib/PublicInbox/Gcf2Client.pm
@@ -15,6 +15,7 @@ use PublicInbox::DS qw(dwaitpid);
 #        sock => writable pipe to Gcf2::loop
 #        in => pipe we read from
 #        pid => PID of Gcf2::loop process
+#        owner_pid => process which spawned {pid}
 sub new  {
         my ($rdr) = @_;
         my $self = bless {}, __PACKAGE__;
@@ -25,6 +26,7 @@ sub new  {
         $rdr //= {};
         $rdr->{0} = $out_r;
         my $cmd = [$^X, qw[-MPublicInbox::Gcf2 -e PublicInbox::Gcf2::loop()]];
+        $self->{owner_pid} = $$;
         @$self{qw(in pid)} = popen_rd($cmd, $env, $rdr);
         fcntl($out_w, 1031, 4096) if $^O eq 'linux'; # 1031: F_SETPIPE_SZ
         $out_w->autoflush(1);
@@ -69,8 +71,10 @@ sub DESTROY {
         delete $self->{in};
         # GitAsyncCat::event_step may reap us with WNOHANG, too
         my $pid = delete $self->{pid} or return;
-        PublicInbox::DS->in_loop ? $self->close : delete($self->{sock});
-        dwaitpid $pid;
+        if ($$ == $self->{owner_pid}) {
+                PublicInbox::DS->in_loop ? $self->close : delete($self->{sock});
+                dwaitpid $pid;
+        }
 }
 
 # used by GitAsyncCat