* [PATCH] listener: warn on some accept()/accept4() errors
@ 2019-10-01 23:18 Eric Wong
0 siblings, 0 replies; only message in thread
From: Eric Wong @ 2019-10-01 23:18 UTC (permalink / raw)
To: meta
We need to warn when hitting file or socket memory limits
or misconfigurations which clear O_NONBLOCK to make it easier
to diagnose configuration problems. We'll also warn on
some other errors in case bugs creep in...
---
lib/PublicInbox/Listener.pm | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/lib/PublicInbox/Listener.pm b/lib/PublicInbox/Listener.pm
index f6a5da69..821c3458 100644
--- a/lib/PublicInbox/Listener.pm
+++ b/lib/PublicInbox/Listener.pm
@@ -10,6 +10,13 @@ use Socket qw(SOL_SOCKET SO_KEEPALIVE IPPROTO_TCP TCP_NODELAY);
use fields qw(post_accept);
require IO::Handle;
use PublicInbox::Syscall qw(EPOLLIN EPOLLEXCLUSIVE EPOLLET);
+use Errno qw(EAGAIN ECONNABORTED EPERM);
+
+# Warn on transient errors, mostly resource limitations.
+# EINTR would indicate the failure to set NonBlocking in systemd or similar
+my %ERR_WARN = map {;
+ eval("Errno::$_()") => $_
+} qw(EMFILE ENFILE ENOBUFS ENOMEM EINTR);
sub new ($$$) {
my ($class, $s, $cb) = @_;
@@ -35,6 +42,18 @@ sub event_step {
IO::Handle::blocking($c, 0); # no accept4 :<
$self->{post_accept}->($c, $addr, $sock);
$self->requeue;
+ } elsif ($! == EAGAIN || $! == ECONNABORTED || $! == EPERM) {
+ # EAGAIN is common and likely
+ # ECONNABORTED is common with bad connections
+ # EPERM happens if firewall rules prevent a connection
+ # on Linux (and everything that emulates Linux).
+ # Firewall rules are sometimes intentional, so we don't
+ # warn on EPERM to avoid being too noisy...
+ return;
+ } elsif (my $sym = $ERR_WARN{int($!)}) {
+ warn "W: accept(): $! ($sym)\n";
+ } else {
+ warn "BUG?: accept(): $!\n";
}
}
--
EW
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2019-10-01 23:18 [PATCH] listener: warn on some accept()/accept4() errors Eric Wong
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