这些是我的宽限期设置（/etc/varnish/default.vcl）
sub vcl_recv { .... set req.grace = 360000s; ... } sub vcl_fetch { ... set beresp.grace = 360000s; ... } 我使用localhost和nodejs作为服务器testing了Varnish。 我开始本地主机，该网站起来了。 然后，我断开服务器，并在2分钟内网站断开连接。 它说：
错误503服务
不可用的服务
不可用的大师
冥想：XID：1890127100
优化caching服务器
你能告诉我可能是什么问题吗？
sub vcl_fetch { if (beresp.ttl < 120s) { ##std.log("Adjusting TTL"); set beresp.ttl = 36000s; ##120s; } # Do not cache the object if the backend application does not want us to. if (beresp.http.Cache-Control ~ "(no-cache|no-store|private|must-revalidate)") { return(hit_for_pass); } # Do not cache the object if the status is not in the 200s if (beresp.status >= 300) { # Remove the Set-Cookie header #remove beresp.http.Set-Cookie; return(hit_for_pass); } # # Everything below here should be cached # # Remove the Set-Cookie header ####remove beresp.http.Set-Cookie; # Set the grace time ## set beresp.grace = 1s; //change this to minutes in case of app shutdown set beresp.grace = 360000s; ## 10 hour - reduce if it has negative impact # Static assets - browser caches tpiphem for a long time. if (req.url ~ "\.(css|js|.js|jpg|jpeg|gif|ico|png)\??\d*$") { /* Remove Expires from backend, it's not long enough */ unset beresp.http.expires; /* Set the clients TTL on this object */ set beresp.http.cache-control = "public, max-age=31536000"; /* marker for vcl_deliver to reset Age: */ set beresp.http.magicmarker = "1"; } else { set beresp.http.Cache-Control = "private, max-age=0, must-revalidate"; set beresp.http.Pragma = "no-cache"; } if (req.url ~ "\.(css|js|min|)\??\d*$") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } ##do not duplicate these settings if (req.url ~ ".css") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } if (req.url ~ ".js") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } if (req.url ~ ".min") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } ## If the request to the backend returns a code other than 200, restart the loop ## If the number of restarts reaches the value of the parameter max_restarts, ## the request will be error'ed. max_restarts defaults to 4. This prevents ## an eternal loop in the event that, eg, the object does not exist at all. if (beresp.status != 200 && beresp.status != 403 && beresp.status != 404) { return(restart); } if (beresp.status == 302) { return(deliver); } # Never cache posts if (req.url ~ "\/post\/" || req.url ~ "\/submit\/" || req.url ~ "\/ask\/" || req.url ~ "\/add\/") { return(hit_for_pass); } ##check this setting to ensure that it does not cause issues for browsers with no gzip if (beresp.http.content-type ~ "text") { set beresp.do_gzip = true; } if (beresp.http.Set-Cookie) { return(deliver); } ##if (req.url == "/index.html") { set beresp.do_esi = true; ##} ## check if this is needed or should be used # return(deliver); the object return(deliver); } sub vcl_recv { ##avoid leeching of images call hot_link; set req.grace = 360000s; ##2m ## if one backend is down - use another if (req.restarts == 0) { set req.backend = cache_director; ##we can specify individual VMs } else if (req.restarts == 1) { set req.backend = cache_director; } ## post calls should not be cached - add cookie for these requests if using micro-caching # Pass requests that are not GET or HEAD if (req.request != "GET" && req.request != "HEAD") { return(pass); ## return(pass) goes to backend - not cache } # Don't cache the result of a redirect if (req.http.Referer ~ "redir" || req.http.Origin ~ "jumpto") { return(pass); } # Don't cache the result of a redirect (asking for logon) if (req.http.Referer ~ "post" || req.http.Referer ~ "submit" || req.http.Referer ~ "add" || req.http.Referer ~ "ask") { return(pass); } # Never cache posts - ensure that we do not use these strings in our URLs' that need to be cached if (req.url ~ "\/post\/" || req.url ~ "\/submit\/" || req.url ~ "\/ask\/" || req.url ~ "\/add\/") { return(pass); } ## if (req.http.Authorization || req.http.Cookie) { if (req.http.Authorization) { /* Not cacheable by default */ return (pass); } # Handle compression correctly. Different browsers send different # "Accept-Encoding" headers, even though they mostly all support the same # compression mechanisms. By consolidating these compression headers into # a consistent format, we can reduce the size of the cache and get more hits. # @see: http:// varnish.projects.linpro.no/wiki/FAQ/Compression if (req.http.Accept-Encoding) { if (req.url ~ "\.(jpg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|ico)$") { # No point in compressing these remove req.http.Accept-Encoding; } else if (req.http.Accept-Encoding ~ "gzip") { # If the browser supports it, we'll use gzip. set req.http.Accept-Encoding = "gzip"; } else if (req.http.Accept-Encoding ~ "deflate") { # Next, try deflate if it is supported. set req.http.Accept-Encoding = "deflate"; } else { # Unknown algorithm. Remove it and send unencoded. unset req.http.Accept-Encoding; } } # lookup graphics, css, js & ico files in the cache if (req.url ~ "\.(png|gif|jpg|jpeg|css|.js|ico)$") { return(lookup); } ##added on 0918 - check if it causes issues with user specific content if (req.request == "GET" && req.http.cookie) { return(lookup); } # Pipe requests that are non-RFC2616 or CONNECT which is weird. if (req.request != "GET" && req.request != "HEAD" && req.request != "PUT" && req.request != "POST" && req.request != "TRACE" && req.request != "OPTIONS" && req.request != "DELETE") { ##closing connection and calling pipe return(pipe); } ##purge content via localhost only if (req.request == "PURGE") { if (!client.ip ~ purge) { error 405 "Not allowed."; } return(lookup); } ## do we need this? ## return(lookup); }
从文档：
为了在后端生病的时候获得宽限时间，必须启用BackendPolling。 否则，后端总是被认为是健康的。