>> On tis, 2008-07-22 at 23:37 +1200, Amos Jeffries wrote: >> >> Only one issue has come up: under sibling relationships, squids method >> of >> relaying requests to sibling is slightly bad and may break the proper >> expected >> behavior. All other setups should be fine. >> >> >>> Also seen in parent relations. >>> >>> Regards Henrik > > Hi, > > What is the nature of the problems with dynamic caching and > sibling/parent relationships? I tried googling for more info but > couldn't find anything. In general dynamic pages should be cachable. There are two cases known to me where that is false. a) page is dynamic, without cache-control info and meant to be non-cachable. This is the reason we add the 0 0% 0 refresh pattern to replace the old QUERY acl. It means consider all indeterminate dynamic requests as non-cacheble. Just to be safe. b) the page is one of the above but has been passed to a peer by squid. This is our fault, squid adds an otherwise unnoticeable cache-control header to requests passed in peering. This breaks the refresh_pattern safety check for (a). None yet has coded the patch for (b). So dynamic caching works in squid, but not on requests received from peers. > > I'm using 4 squid nodes [2.7STABLE3] as accelerators and encountered > some odd behavior recently after enabling dynamic caching. There are > sibling relationships among the 4 nodes using ICP and cache digests. > Under medium load I've been able to successfully cache and serve > dynamic URLs: > > GET http://contentreal.foobar.com/clown_widget.swf?version=20080820 > STORE_OK IN_MEMORY SWAPOUT_NONE PING_NONE > CACHABLE,VALIDATED > > But under heavier load [20-50mbit per node] I get multiple objects [20-30] > like: > > GET http://contentreal.foobar.com/clown_widget.swf?version=20080820 > STORE_PENDING NOT_IN_MEMORY SWAPOUT_NONE PING_DONE > RELEASE_REQUEST,DISPATCHED,PRIVATE,VALIDATED > > GET http://contentreal.foobar.com/clown_widget.swf?version=20080820 > STORE_OK NOT_IN_MEMORY SWAPOUT_NONE PING_DONE > RELEASE_REQUEST,DISPATCHED,PRIVATE,VALIDATED,ABORTED > > and requests for this URL timeout after about 25-50% of the download is > done. > > Headers are being set via apache/mod_expires: > > [root@mongo ~]# curl -I > http://content5.foobar.com/clown_widget.swf?version=20080820 > HTTP/1.0 200 OK > Date: Thu, 21 Aug 2008 09:53:50 GMT > Server: Apache > Last-Modified: Fri, 08 Aug 2008 06:07:10 GMT > ETag: "35b0f" > Accept-Ranges: bytes > Content-Length: 219919 > Cache-Control: max-age=86400 > Expires: Fri, 22 Aug 2008 09:53:50 GMT > Content-Type: application/x-shockwave-flash > X-Cache: MISS from squid03.foobar.com > X-Cache-Lookup: MISS from squid03.foobar.com:80 > Via: 1.1 squid03.foobar.com:80 (squid) > Connection: close > > I followed http://wiki.squid-cache.org/ConfigExamples/DynamicContent, > acl QUERY is disabled and the swf is < maximum_object_size_in_memory. > Any assistance would be greatly appreciated. > > Thanks to all who maintain squid, this is great and extremely useful > software. > > murray > > ##### squid.conf ##### > http_port 80 defaultsite=contentreal.foobar.com > cache_peer 110.0.2.99 parent 80 0 no-query no-digest originserver > cache_peer 110.0.2.76 sibling 80 3130 > cache_peer 110.0.2.77 sibling 80 3130 proxy-only > cache_peer 110.0.2.78 sibling 80 3130 proxy-only > digest_generation on > #hierarchy_stoplist cgi-bin ? > #acl QUERY urlpath_regex cgi-bin \? > #cache deny QUERY > shutdown_lifetime 10 seconds > strip_query_terms off > acl apache rep_header Server ^Apache > broken_vary_encoding allow apache > cache_mem 5200 MB > maximum_object_size_in_memory 500 KB > ipcache_size 4096 > fqdncache_size 4096 > cache_dir null /tmp > logformat squid %tl.%03tu %6tr %>a %Ss/%03Hs %<st %rm %ru %un %Sh/%<A %mt > access_log /usr/local/squid/var/logs/access.log squid > negative_ttl 30 seconds > cache_access_log /dev/null > cache_store_log /dev/null > buffered_logs on > client_db off > refresh_pattern html$ 0 20% 1 > refresh_pattern txt$ 0 20% 1 > refresh_pattern xml$ 0 20% 5 > refresh_pattern swf$ 0 20% 5 > refresh_pattern flv$ 0 20% 10 > refresh_pattern . 0 20% 4320 > refresh_pattern (cgi-bin|\?) 0 0% 0 > #refresh_pattern ^ftp: 1440 20% 10080 > #refresh_pattern ^gopher: 1440 0% 1440 > acl N1 src 110.0.2.76 > acl N2 src 110.0.2.77 > acl N3 src 110.0.2.78 > icp_access allow N1 > icp_access allow N2 > icp_access allow N3 > acl all src 0.0.0.0/0.0.0.0 > acl manager proto cache_object > acl localhost src 127.0.0.1/255.255.255.255 > acl to_localhost dst 127.0.0.0/8 > acl SSL_ports port 443 > acl Safe_ports port 80 # http > acl CONNECT method CONNECT > acl purge method PURGE > http_access allow purge localhost > http_access deny purge > http_access allow manager localhost > http_access deny manager > http_access deny !Safe_ports > http_access deny CONNECT !SSL_ports > http_access allow localhost > http_access allow all > http_reply_access allow all > cache_mgr webmaster@xxxxxxxxxx > cache_effective_user squidmaster > httpd_suppress_version_string on > coredump_dir /usr/local/squid/var/cache > > ##### config.log ##### > ./configure --enable-storeio=null,aufs,diskd,ufs --enable-cache-digests >
