Good detective work! I'm not sure whether this is a requirement or not. Henrik would know better. Henrik, is this worthy of a bugzilla report? adrian 2008/11/30 Itzcak Pechtalt <itzcak@xxxxxxxxx>: > Hi > > I found some inefficiency in Squid TCP connection handling toward servers . > In some cases Squid closes TCP connection to servers immediately after > 304 not modified response and doesn't save it for reuse. > There is no visbible reason why Squid closes the connection. Squid > Sends "Connection: Keep-Alive" in HTTP request and the web server > returns "Connection: Keep-Alive" on the response, Also pconn_timeout > is configured to 1 minute. > > After digging into the problem, I found that the the problem occurs > only in cases the object type is PRIVATE. It seems like when > client_side code hadnles 304 not modified reply it calls > store_unregister which closes store entry and TCP connection in turn. > > To reproduce it do the following > 1) Browse www.cnn.com > 2) Delete browser cache. > 3) Browse again. The case will occur here. > > Does someone know about it ? > > Itzcak > > Following short Wireshark sniff with 1 sample, 10.50.0.100 is Squid > IP. See FIN packet from Squid. > > 0.000000 10.50.0.100 -> 205.128.90.126 TCP 4006 > http [SYN] Seq=0 > Len=0 MSS=1460 WS=2 > 0.085216 205.128.90.126 -> 10.50.0.100 TCP http > 4006 [SYN, ACK] > Seq=0 Ack=1 Win=5840 Len=0 MSS=1460 WS=7 > 0.085226 10.50.0.100 -> 205.128.90.126 TCP 4006 > http [ACK] Seq=1 > Ack=1 Win=5840 Len=0 > 0.085230 10.50.0.100 -> 205.128.90.126 HTTP GET > /cnn/.element/css/2.0/common.css HTTP/1.0 > GET /cnn/.element/css/2.0/common.css HTTP/1.0 > If-Modified-Since: Tue, 16 Sep 2008 14:48:32 GMT > Accept: */* > Referer: http://www.cnn.com/ > Accept-Language: en-us > UA-CPU: x86 > User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET > CLR 2.0.50727; .NET CLR 3.0.04506.30) > Host: i.cdn.turner.com > Cache-Control: max-age=259200 > Connection: keep-alive > > 0.172250 205.128.90.126 -> 10.50.0.100 TCP http > 4006 [ACK] Seq=1 > Ack=366 Win=6912 Len=0 > 0.172934 205.128.90.126 -> 10.50.0.100 HTTP HTTP/1.1 304 Not Modified > HTTP/1.1 304 Not Modified > Date: Wed, 26 Nov 2008 12:33:33 GMT > Expires: Wed, 26 Nov 2008 13:03:51 GMT > Last-Modified: Tue, 16 Sep 2008 14:48:32 GMT > Cache-Control: max-age=3600 > Connection: keep-alive > > 0.173145 10.50.0.100 -> 205.128.90.126 TCP 4006 > http [ACK] Seq=366 > Ack=206 Win=6912 Len=0 > 0.173238 10.50.0.100 -> 205.128.90.126 TCP 4006 > http [FIN, ACK] > Seq=366 Ack=206 Win=6912 Len=0 > 0.259520 205.128.90.126 -> 10.50.0.100 TCP http > 4006 [FIN, ACK] > Seq=206 Ack=367 Win=6912 Len=0 > 0.259906 10.50.0.100 -> 205.128.90.126 TCP 4006 > http [ACK] Seq=367 > Ack=207 Win=6912 Len=0 > 0.565702 205.128.90.126 -> 10.50.0.100 TCP http > 4006 [FIN, ACK] > Seq=206 Ack=367 Win=6912 Len=0 > 0.565842 10.50.0.100 -> 205.128.90.126 TCP [TCP Dup ACK 10#1] 4006 > > http [ACK] Seq=367 Ack=207 Win=6912 Len=0 > >
