ref: 86bb3c77dd2f80dc823437f1cf48d2e654a68e93
parent: b1173e1e554b71ae20cc5a421350700c3d099165
author: sl <sl@stanleylieber.com>
date: Fri Feb 19 16:29:55 EST 2021
/sys/src/cmd/ndb/dns.h: --- To: 9front@9front.org Date: Sun, 07 Feb 2021 14:56:39 +0100 From: kvik@a-b.xyz Subject: Re: [9front] transient dns errors cause smtp failure Reply-To: 9front@9front.org I think I found a reason for DNS failing on known good domains. /sys/src/cmd/ndb/dns.h:156,157 /* tune; was 60*1000; keep it short */ Maxreqtm= 8*1000, /* max. ms to process a request */ So, 8 seconds is how much the resolver will bother with a request it has been handed, before dropping it on the floor with little explanation. It seems quite possible that this is too short a timeout on a machine during a spam queue run, which predictably stresses the compute and network resources. In turn, negative response caching might explain why a particular unlucky domain would basically stop receiveing any mail for a while. I'm dying to know if bumping this limit would clear up the queue of such DNS errors. --- [narrator: it did.]
--- a/sys/src/cmd/ndb/dns.h
+++ b/sys/src/cmd/ndb/dns.h
@@ -151,8 +151,8 @@
/* parallelism: tune; was 32; allow lots */
Maxactive= 250,
- /* tune; was 60*1000; keep it short */
- Maxreqtm= 8*1000, /* max. ms to process a request */
+ /* tune; was 8*1000; that was too short */
+ Maxreqtm= 60*1000, /* max. ms to process a request */
Notauthoritative = 0,
Authoritative,
--
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