ref: 4bbb3b0b21edd81be37a0a6ad12c76a63d127bed
parent: 29e8ea26f2f9af2b9924e16dffd784bc5ae5685e
author: sl <[email protected]>
date: Fri Feb 19 16:29:55 EST 2021
/sys/src/cmd/ndb/dns.h: --- To: [email protected] Date: Sun, 07 Feb 2021 14:56:39 +0100 From: [email protected] Subject: Re: [9front] transient dns errors cause smtp failure Reply-To: [email protected] 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,