'Resource temporarily unavailable'

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82372: 1.466959344 accept4(0x8,0x7fffffffe7a0,0x7fffffffe798,0x20000000) = 14 (0xe)
82372: 1.467039572 setsockopt(14,IPPROTO_TCP,TCP_NODELAY,0x578174,4) = 0 (0x0)
82372: 1.467097580 accept4(0x8,0x7fffffffe7a0,0x7fffffffe798,0x20000000) ERR#35 ‘Resource temporarily unavailable’

HA-Proxy version 1.8.4-de425f6 2018/02/26
Copyright 2000-2018 Willy Tarreau willy@haproxy.org

Build options :
TARGET = freebsd
CPU = generic
CC = cc
CFLAGS = -O2 -pipe -fstack-protector -fno-strict-aliasing -fno-strict-aliasing -Wdeclaration-after-statement -fwrapv -Wno-address-of-packed-member -Wno-null-dereference -Wno-unused-label -DFREEBSD_PORTS
OPTIONS = USE_GETADDRINFO=1 USE_ZLIB=1 USE_CPU_AFFINITY=1 USE_ACCEPT4=1 USE_REGPARM=1 USE_OPENSSL=1 USE_LUA=1 USE_STATIC_PCRE=1 USE_PCRE_JIT=1

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

Built with network namespace support.
Built with zlib version : 1.2.11
Running on zlib version : 1.2.11
Compression algorithms supported : identity(“identity”), deflate(“deflate”), raw-deflate(“deflate”), gzip(“gzip”)
Built with PCRE version : 8.40 2017-01-11
Running on PCRE version : 8.40 2017-01-11
PCRE library supports JIT : yes
Built with multi-threading support.
Encrypted password support via crypt(3): yes
Built with transparent proxy support using: IP_BINDANY IPV6_BINDANY
Built with Lua version : Lua 5.3.4
Built with OpenSSL version : OpenSSL 1.0.2k-freebsd 26 Jan 2017
Running on OpenSSL version : OpenSSL 1.0.2k-freebsd 26 Jan 2017
OpenSSL library supports TLS extensions : yes
OpenSSL library supports SNI : yes
OpenSSL library supports : SSLv3 TLSv1.0 TLSv1.1 TLSv1.2

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

Available filters :
[TRACE] trace
[COMP] compression
[SPOE] spoe