Hello, Finally, I've composed all the work I did this year about mod_proxy functionality as a dynamic content cache, into one patchset. This job was done during while developing and maintaining websites produced by http://web.masterskaya.ru (sorry, we have no english page yet). Those website include http://www.polit.ru, largest russian politics site, http://www.izvestia.ru, website of one of the major russian newspapers, and many, many others. We handle about 1 000 000 http hits per day with common dual httpd model - lightweight frontend with mod_proxy and heavy backend with mod_perl. You can download diffs from here: http://web.masterskaya.ru/~ilya/xfire_patches.tar.gz DISCLAIMER I'm not responsible for any damage, lost profit, or any other disasters caused by the code. DESCRIPTION OF FIXES Fixes was done for apache version 1.3.9. But I think it should work with 1.3.4 and higher versions too. I've not tested it with versions other than 1.3.9, and I've not tested it on Win32 platform. 1) Subtle problem with mod_include/mod_rewrite/mod_proxy. mod_include reports error when receiving response code other than HTTP_OK. So I've fixed mod_proxy so that it can return HTTP_NOT_MODIFIED only if request is not subrequest. Also, I've enabled mod_rewrite ruleflag [P] on subrequests. 2) Large amount of reloads cause very high load on backend because requests bypass the cache. I've added IgnoreNoCache <filemask> directive to mod_proxy config. <Filemask> is a mask for frontend server URIs. When mask is matched, Pragma: no-cache header is being deleted from incoming file headers, so if cached data present, it would be returned instead of getting data from backend server. 3) On site with a very high traffic, there's a real risk of simultaneous reloading of the same URI by numerous clients. This is also causes problems on backend, especially with complicated dynamically-generated pages. I've fixed this by adding mod_proxy directive NoConcurrentCacheUpdates (On|Off), and new scoreboard status SERVER_PROXY_READ. When the flag is on and expired data found, server first checks if this URI is being downloaded from upstream by any other child. If so, it returns expired data to client while 'downloading' child doing its job of updating the cache. 4) I've added X-Real-IP header to present real IP to the backend server. I think that X-Forwarded-For is for REAL proxies, so I don't want to mess with it. 5) I've replaced ExplainX macros in proxy_cache.c for ap_log_rerror API call. Seems that those macros don't work, dunno why... So, that is all and here it is. Enjoy. Best regards, Ilya mailto:[EMAIL PROTECTED]
