I'm running a reverse proxy on CentOS5 with squid-2.6.STABLE6-5.el5_1.2 (RHEL RPM) and running into some odd issues. I have a stack setup like this: Squid (port 80) -> apache (port 8888) -> Resin (port 8080) It's caching images/static files served from the apache level like a champ, but it's having intermittent problems caching dynamically generate content. The apache -> Resin connector is mod_proxy_http with the "force-proxy-request-1.0" hack in-place. Apache is 2.2.8, Resin 3.1.3, all running on the same box - Linux devserver01 2.6.18-53.1.4.el5 #1 SMP Fri Nov 30 00:45:55 EST 2007 x86_64 x86_64 x86_64 GNU/Linux. Running once a second a curl command like: curl -b /tmp/cj -c /tmp/cj -s -v -o/dev/null http://www.example.com/index.html I'll get this response dozens/hundreds of times (i.e. a MISS): * About to connect() to www.example.com port 80 * Trying 192.168.80.223... connected * Connected to www.example.com (192.168.80.223) port 80 > GET /index.html HTTP/1.1 > User-Agent: curl/7.15.5 (x86_64-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8b zlib/1.2.3 libidn/0.6.5 > Host: www.example.com > Accept: */* > Cookie: JSESSIONID=abciW-MVH28Db_ekbG5Gr > < HTTP/1.0 200 OK < Date: Thu, 21 Feb 2008 23:31:55 GMT < Server: Resin/3.1.3 < Cache-Control: max-age=60, must-revalidate, proxy-revalidate < Expires: Thu, 21 Feb 2008 23:32:54 GMT < Content-Type: text/html; charset=iso-8859-1 < X-Cache: MISS from devserver01.example.com < X-Cache-Lookup: MISS from devserver01.example.com:80 < Via: 1.0 devserver01.example.com:80 (squid) < Connection: close Closing connection #0 But then all of a sudden I'll get this for a minute as the Age counter increments up to max-age, 60: * About to connect() to www.example.com port 80 * Trying 192.168.80.223... connected * Connected to www.example.com (192.168.80.223) port 80 > GET /index.html HTTP/1.1 > User-Agent: curl/7.15.5 (x86_64-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8b zlib/1.2.3 libidn/0.6.5 > Host: www.example.com > Accept: */* > Cookie: JSESSIONID=abciW-MVH28Db_ekbG5Gr > < HTTP/1.0 200 OK < Date: Thu, 21 Feb 2008 23:31:55 GMT < Server: Resin/3.1.3 < Cache-Control: max-age=60, must-revalidate, proxy-revalidate < Expires: Thu, 21 Feb 2008 23:32:54 GMT < Content-Type: text/html; charset=iso-8859-1 < Age: 2 < X-Cache: HIT from devserver01.example.com < X-Cache-Lookup: HIT from devserver01.example.com:80 < Via: 1.0 devserver01.example.com:80 (squid) < Connection: close Closing connection #0 and then it will go back to an un-cached, MISS state for dozens/hundreds of requests. Given the Cache-Control / Expires headers, shouldn't Squid be caching this every single time for sixty seconds? Tony P.S. The site involved here gets hundreds/thousands of hits per second for these pages, so caching for 60 seconds is a big win. We'll extend cache times as required... once it's working.
