qspawn: catch transient errors on pipe, EPOLL_CTL_ADD

popen_rd dies on pipe()/pipe2() failure due to FD exhaustion.

EPOLL_CTL_ADD (via PublicInbox::HTTPD::Async->new) may also fail
due to memory exhaustion or exceeding the value of
/proc/sys/fs/epoll/max_user_watches

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 65bb178aba44a216f73c221338aebd5f7a9dba92..31a1583dfebcef7d6f9a25749493f63fce563f9a 100644 (file)
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -45,25 +45,28 @@ sub new ($$$;) {
 sub _do_spawn {
        my ($self, $start_cb, $limiter) = @_;
        my $err;
-       my ($cmd, $cmd_env, $opts) = @{$self->{args}};
-       my %opts = %{$opts || {}};
+       my ($cmd, $cmd_env, $opt) = @{$self->{args}};
+       my %o = %{$opt || {}};
        $self->{limiter} = $limiter;
        foreach my $k (PublicInbox::Spawn::RLIMITS()) {
                if (defined(my $rlimit = $limiter->{$k})) {
-                       $opts{$k} = $rlimit;
+                       $o{$k} = $rlimit;
                }
        }
+       eval {
+               # popen_rd may die on EMFILE, ENFILE
+               ($self->{rpipe}, $self->{pid}) = popen_rd($cmd, $cmd_env, \%o);
+               $self->{args} = $o{quiet} ? undef : $cmd;
 
-       ($self->{rpipe}, $self->{pid}) = popen_rd($cmd, $cmd_env, \%opts);
+               die "E: $!" unless defined($self->{pid});
 
-       $self->{args} = $opts{quiet} ? undef : $cmd;
-
-       if (defined $self->{pid}) {
                $limiter->{running}++;
-       } else {
-               $self->{err} = $!;
+               $start_cb->($self); # EPOLL_CTL_ADD may ENOSPC/ENOMEM
+       };
+       if ($@) {
+               $self->{err} = $@;
+               finish($self);
        }
-       $start_cb->($self);
 }
 
 sub child_err ($) {
@@ -105,7 +108,11 @@ sub waitpid_err ($$) {
        }
 
        if ($err) {
-               $self->{err} = $err;
+               if ($self->{err}) {
+                       $self->{err} .= "; $err";
+               } else {
+                       $self->{err} = $err;
+               }
                if ($env && $self->{args}) {
                        log_err($env, join(' ', @{$self->{args}}) . ": $err");
                }