On Mon, 2015-06-01 at 21:44 +0200, Reindl Harald wrote: > Am 01.06.2015 um 21:38 schrieb Andrew Lutomirski: > > On Mon, Jun 1, 2015 at 12:29 PM, Chris Adams <linux@xxxxxxxxxxx> wrote: > >> Once upon a time, Andrew Lutomirski <luto@xxxxxxx> said: > >>> I'm with Jason here. Glibc's resolver is amazingly buggy, and things > >>> break randomly and unreproducibly when this happens. A good setup > >>> would have a local resolver and glibc would be configured to cache > >>> nothing whatsoever. Then, if you need to perform maintenance on the > >>> local DNS cache, you can do it by flushing your local resolver rather > >>> than trying to figure out how you're going to persuade every running > >>> program to tell glibc to flush its cache. > >> > >> glibc doesn't have a cache, except each process caching the settings in > >> /etc/resolv.conf. That's part of the problem, because there's no way to > >> cache "first server in resolv.conf is not responding", so each lookup > >> has to figure that out for itself (many timeouts). > > > > Glibc caches *something* that enabled the bug I hit. I don't know > > exactly what it's trying to cache, but it's certainly stateful > > it don't cache dns respones - try it out in your local network > *client applications* may cache respones > > try it out in your local network > > * enter a non existing subdomain in firefox > * add the hostname to your LAN nameserver > * try again: firefox refuses > * restart just firefox > * it resolves without any delay > > a) that proves no systemwide cachae > b) it proves with introduce a local systemdwide cache > you introduce a problem not existing before > If you have nscd running glibc caches, so it is a matter of configuration. The *only* reason why Firefox caches Names is because we do not have a local dns caching resolver, so Firefox had to implement its own. If you had a local caching resolver Firefox could be changed to stop caching on its own instead. Which would be a plus, I often have way too many tabs open to consider restarting firefox unless the website with issues is really important. If i had a local resolver it would be easy to just flush that one and have FF back in business immediately. As you see it is a matter of perspective. Simo. -- Simo Sorce * Red Hat, Inc * New York -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
