Using req/obj.grace to serve stale objects when backend fails
I've experimented with req/obj.grace set to a few hours so a site can be served even if the backend fails. For example, with the backend down and when req/obj.grace is set to several hours I can open a new browser and get a 503 if I try to open a known cached (and graced) page. However if I refresh the same browser several times very rapidly I finally receive the graced page. It seems to be working as expected from what I read in the documentation regarding the graced object being served while the same object is being fetched by another thread. The rapid refreshing is generating a second thread request which then satisifies the requirements to have the graced object served. Is there a way to configure varnish to serve the cached graced object if the backend fails without the browser ever seeing the 503? Can this also be tied into the backend probing/polling? Thanks, --J ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: Using req/obj.grace to serve stale objects when backend fails
Hi, On Thu, Nov 06, 2008 at 06:05:46PM -0800, Jeff Anderson wrote: I've experimented with req/obj.grace set to a few hours so a site can be served even if the backend fails. For example, with the backend down and when req/obj.grace is set to several hours I can open a new browser and get a 503 if I try to open a known cached (and graced) page. However if I refresh the same browser several times very rapidly I finally receive the graced page. It seems to be working as expected from what I read in the documentation regarding the graced object being served while the same object is being fetched by another thread. The rapid refreshing is generating a second thread request which then satisifies the requirements to have the graced object served. Is there a way to configure varnish to serve the cached graced object if the backend fails without the browser ever seeing the 503? Can this also be tied into the backend probing/polling? It's not possible yet, but wanted. See ticket http://varnish.projects.linpro.no/ticket/369. You may also have an interest for http://varnish.projects.linpro.no/wiki/VCLExampleRestarts. Cheers, -- Anders. ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Re: Using req/obj.grace to serve stale objects when backend fails
Hi Jeff. Jeff Anderson skrev: I've experimented with req/obj.grace set to a few hours so a site can be served even if the backend fails. For example, with the backend down and when req/obj.grace is set to several hours I can open a new browser and get a 503 if I try to open a known cached (and graced) page. You're right. It shold be fixed. There is now a ticket (#369) on the matter. -- http://linpro.no/ | http://redpill.se/ signature.asc Description: OpenPGP digital signature ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
Using req/obj.grace to serve stale objects when backend fails
Sorry for the second post. I've experimented with req/obj.grace set to a few hours so a site can be served even if the backend fails. For example, with the backend down and when req/obj.grace is set to several hours I can open a new browser and get a 503 if I try to open a known cached (and graced) page. However if I refresh the same browser several times very rapidly I finally receive the graced page. It seems to be working as expected from what I read in the documentation regarding the graced object being served while the same object is being fetched by another thread. The rapid refreshing is generating a second thread request which then satisifies the requirements to have the graced object served. Is there a way to configure varnish to serve the cached graced object if the backend fails without the browser ever seeing the 503? Can this also be tied into the backend probing/polling to serve the graced page if all the backends fail? Thanks, --J ___ varnish-misc mailing list varnish-misc@projects.linpro.no http://projects.linpro.no/mailman/listinfo/varnish-misc
