Possible regression in 1.6.12 (1 reply)

Possible regression in 1.6.12

I might have discovered a haproxy bug. It occurs when all of the
following configuration conditions are satisfied:
* haproxy version 1.6.12
* multiple processes
* resolvers section with more than one server configured (not even used
anywhere)
* haproxy is either reloaded or restarted
* request is made against freshly reloaded/restarted haproxy or haproxy
backend server health check is made. Both cases requests do not get
response.

When accessing haproxy, requests time out. Backends will fail checks and
are marked as down with timeout error. Happens with browsers, curl,
wget. When downgrading to 1.6.11, timeouts don't happen.

How I tested:
1) reload haproxy with the minimal config below
2) then run: for i in {1..100}; do date --utc; echo $i; curl
https://tsthost.tld/haproxy?stats -o /dev/null -s -m 50; done
Wed 14 Jun 11:45:44 UTC 2017
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When removing either multiprocess configuration or resolvers section, no
requests time out.

Following is trimmed down minimal config:
global
daemon
nbproc 3
maxconn 500
user haproxy
tune.ssl.default-dh-param 2048
ssl-default-bind-options no-sslv3 no-tls-tickets
ssl-default-bind-ciphers
AES128+EECDH:AES128+EDH:!ADH:!AECDH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!3DES:!MD5:!PSK
ssl-default-server-options no-sslv3 no-tls-tickets
ssl-default-server-ciphers
AES128+EECDH:AES128+EDH:!ADH:!AECDH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!3DES:!MD5:!PSK
stats socket /var/run/haproxy1.sock mode 600 process 1
stats socket /var/run/haproxy2.sock mode 600 process 2
stats socket /var/run/haproxy3.sock mode 600 process 3

defaults
bind-process 3
log /dev/log local0
option log-health-checks
option contstats
timeout connect 10s
timeout client 60s
timeout server 60s

resolvers dns_resolvers
# local caching named
nameserver dns0 127.0.0.1:53
# remote servers
nameserver dns1 8.8.8.8:53
nameserver dns2 8.8.4.4:53

listen ssl-frontend
bind-process 1-2
bind *:443 ssl crt /path/to/certificate.pem
server http-frontend 127.0.0.1:666 send-proxy check

frontend http-frontend
mode http
stats enable
option forwardfor
option httplog
bind *:80
bind 127.0.0.1:666 accept-proxy

backend ssl_backend
mode http
option httplog
server ssl_server google.com:443 check ssl verify none fall 2 inter
5s fastinter 3s rise 3


HA-Proxy version 1.6.12 2017/04/04
Copyright 2000-2017 Willy Tarreau <willy@haproxy.org>

Build options :
TARGET = linux2628
CPU = generic
CC = gcc
CFLAGS = -m64 -march=x86-64 -O2 -g -fno-strict-aliasing
-Wdeclaration-after-statement
OPTIONS = USE_ZLIB=1 USE_OPENSSL=1 USE_LUA=1 USE_PCRE=1

Default settings :
maxconn = 2000, bufsize = 16384, maxrewrite = 1024, maxpollevents = 200

Encrypted password support via crypt(3): yes
Built with zlib version : 1.2.3
Running on zlib version : 1.2.7
Compression algorithms supported : identity("identity"),
deflate("deflate"), raw-deflate("deflate"), gzip("gzip")
Built with OpenSSL version : OpenSSL 1.0.1e-fips 11 Feb 2013
Running on OpenSSL version : OpenSSL 1.0.1e-fips 11 Feb 2013
OpenSSL library supports TLS extensions : yes
OpenSSL library supports SNI : yes
OpenSSL library supports prefer-server-ciphers : yes
Built with PCRE version : 7.8 2008-09-05
Running on PCRE version : 7.8 2008-09-05
PCRE library supports JIT : no (USE_PCRE_JIT not set)
Built with Lua version : Lua 5.3.3
Built with transparent proxy support using: IP_TRANSPARENT
IPV6_TRANSPARENT IP_FREEBIND

Available polling systems :
epoll : pref=300, test result OK
poll : pref=200, test result OK
select : pref=150, test result OK
Total: 3 (3 usable), will use epoll.