2012/9/27 Jenny Lee <bodycar...@live.com>: > > > ---------------------------------------- >> Date: Thu, 27 Sep 2012 21:08:12 +0200 >> From: e...@g.jct.ac.il >> To: t...@raynersw.com >> CC: squid-users@squid-cache.org >> Subject: Re: [squid-users] clarification of delay_initial_bucket_level >> >> 2012/9/27 t...@raynersw.com <t...@raynersw.com>: >> >> Hmm, I just noticed Eliazers' reply about how reloading often is a bad >> >> idea and one should use ext_acls instead, >> > >> > I'd be interested to hear why reloading is a bad idea. Squid supports HUP >> > reloading, I've been doing it for years and on my systems it takes about >> > 100ms to do a reload, so even if it blocks for that amount of time it's >> > not a big deal. Unless the reload leaks memory or something, I don't think >> > it's a problem. I have an action item to move my servers to external ACLs, >> > but it's been one of those "if it ain't broke" type things, so I haven't >> > done it yet. >> > >> >> I don't think Eliezer meant reloading per se as much as my question >> which was reloading every 5 minutes. >> I also reload all the time when I write new configs and sometimes I >> even end up reloading several times in one minute without my users >> feeling it as far as I can tell (or at least they don't feel it enough >> to start sending mail saying the Internet is broken). > > You can be sure that they feel it. But they are not able to complain because > duration is short and they are not sure if the problem is arising on their > end or elsewhere. > Why don't you just run a cron job to reconfigure squid every minute and try > to keep browsing? > Bad things can and do happen when squid stops servicing connections while > active sessions are going on. If your shutdown timeout is short, you are > probably cutting off existing connections abruptly as well. Browsers and OSes > behave weirdly. Once a user even had to reboot his computer to be able to get > back online when subjected to a reconfigure. > Squid also will surely will take more than few seconds to get back online > even with the minimal config options (maybe tcr can explain how he came up > with 100ms). In my config, it takes 3 seconds (with shutdown_timeout 1). When > you are doing 500 requests per second, those couple of seconds mean you lose > couple thousand requests, and you probably cut couple thousand in the middle. > Moreover, it takes about 1.5 minutes for squid to get back to the speed it > was doing before a reconfigure (probably because client machines are waiting > for timeouts on failed requests). And I don't even do caching! > Moral of the story is... despite Amos's efforts to make it less burdensome on > 3.2's, frequent reconfigures must be avoided. > Jenny > > PS: I do a reconfigure once an hour, but my traffic is controlled.
Jenny as far as I can tell from your mail you are running a restart (service squid3 restart or /etc/init.d/squid3 restart) and not a reload, reloads in my experience are very fast, they fix almost everything and are close to unfelt by the users, I have had streams running in a browser while I reloaded and they just continued with no problem (but that may also be effective caching on the websites part). Eli
