user/dev discussion of public-inbox itself
 help / color / Atom feed
* [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


^ permalink raw reply	[flat|nested] only message in thread

only message in thread, back to index

Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-01 23:18 [PATCH] listener: warn on some accept()/accept4() errors Eric Wong

user/dev discussion of public-inbox itself

Archives are clonable:
	git clone --mirror http://public-inbox.org/meta
	git clone --mirror http://czquwvybam4bgbro.onion/meta
	git clone --mirror http://hjrcffqmbrq6wope.onion/meta
	git clone --mirror http://ou63pmih66umazou.onion/meta

Example config snippet for mirrors

Newsgroups are available over NNTP:
	nntp://news.public-inbox.org/inbox.comp.mail.public-inbox.meta
	nntp://ou63pmih66umazou.onion/inbox.comp.mail.public-inbox.meta
	nntp://czquwvybam4bgbro.onion/inbox.comp.mail.public-inbox.meta
	nntp://hjrcffqmbrq6wope.onion/inbox.comp.mail.public-inbox.meta
	nntp://news.gmane.org/gmane.mail.public-inbox.general

 note: .onion URLs require Tor: https://www.torproject.org/

AGPL code for this site: git clone https://public-inbox.org/ public-inbox