[squid-users] forward_max_tries 1 has no effect

[Ivan Larionov]

Hello.

We have an issue with squid when it tries to re-forward / retry failed
request even when forward_max_tries is set to 1. The situation when it
happens is when there's no response, parent just closes the connection.

Relevant parts of configuration so you understand the architecture:

cache_peer 127.0.0.1 parent 18070 0 no-query no-digest no-netdb-exchange
name=proxy
never_direct allow all
negative_ttl 0 seconds
forward_max_tries 1
retry_on_error off

The traffic flow from tcpdump is like this:

squid to parent
GET http://HOST/
parent to squid
ACK

waiting (no response for ~40 seconds)

parent to squid
FIN, ACK
squid to parent
FIN, ACK
parent to squid
FIN

Immediately after that:

squid to parent
GET http://HOST/ (again)

Debug logs from ALL,2:

…
http.cc(2229) sendRequest: HTTP Server local=127.0.0.2:46867 remote=
127.0.0.1:18070 FD 26 flags=1
http.cc(2230) sendRequest: HTTP Server REQUEST:
---------
GET http://HOST:12345/ HTTP/1.1
…
http.cc(1299) continueAfterParsingHeader: WARNING: HTTP: Invalid Response:
No object data received for http://HOST:12345/ AKA HOST/
FwdState.cc(655) handleUnregisteredServerEnd: self=0x430a438*2
err=0x445fcf8 http://HOST:12345/
http.cc(2229) sendRequest: HTTP Server local=127.0.0.2:34417 remote=
127.0.0.1:18070 FD 26 flags=1
http.cc(2230) sendRequest: HTTP Server REQUEST:
---------
GET http://HOST:12345/ HTTP/1.1
…

It doesn't happen 100% times. Sometimes squid returns 502 after the 1st
try, sometimes it retries once. Also I haven't seen more than 1 retry.

Could it be a bug? We'd really like to disable these retries.

Squid Cache: Version 3.5.27
Service Name: squid
configure options:  '--program-prefix=' '--prefix=/usr'
'--exec-prefix=/usr' '--bindir=/usr/sbin' '--sbindir=/usr/sbin'
'--sysconfdir=/etc/squid' '--libdir=/usr/lib' '--libexecdir=/usr/lib/squid'
'--includedir=/usr/include' '--datadir=/usr/share'
'--sharedstatedir=/usr/com' '--localstatedir=/var'
'--mandir=/usr/share/man' '--infodir=/usr/share/info' '--enable-epoll'
'--enable-removal-policies=heap,lru' '--enable-storeio=aufs,rock'
'--enable-delay-pools' '--with-pthreads' '--enable-cache-digests'
'--with-large-files' '--with-maxfd=16384' '--enable-htcp'

-- 
With best regards, Ivan Larionov.
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