Re: [squid-users] Squid Reconfigure Downtime
On 5/5/22 21:33, Manikandan Swaminathan wrote: We're currently running Squid 4.8, and I want to know, what is the expected downtime when running "squid -k reconfigure"? The actual delay depends on many variables, including the definition of "downtime". Very roughly speaking, reconfiguration today can be almost as heavy/slow (or as light/fast) as starting Squid from scratch. Certain startup actions (e.g., building an in-memory index of cache_dirs) are skipped during reconfigurations, and some optimizations (e.g., various internal caches) continue to work through reconfigurations, but a lot of heavy startup actions are performed during reconfigurations as well. How does this affect existing and incoming connections? Most existing connections, especially short-lived ones, are usually unaffected when the configuration does not change much. IIRC, new incoming connections may be rejected during reconfiguration (in some cases). The code is not written to guarantee much: Squid does _not_ maintain a consistent configuration state during (re)configuration. YMMV. I ran a simple test in my machine where I reconfigure squid, while separately running multiple proxy requests. As far as I could tell, there wasn't any disruption, but I'd like to get some input from more experienced folks. Your test did not expose existing problems. I do not know how much those problems are going to affect your deployment environment. FWIW, we have an ongoing "smooth reconfiguration" project that makes Squid reconfigure just the changed configuration directives, without disrupting traffic. It will take a while to cover all configuration directives, but I hope to see the first pull requests that cover some directives soon. HTH, Alex. ___ squid-users mailing list squid-users@lists.squid-cache.org http://lists.squid-cache.org/listinfo/squid-users
Re: [squid-users] Squid Reconfigure Downtime
Hey Mani, With “squid -k reconfigure” there shouldn’t be down time. There are special scenarios which the complexity or the length of the configuration files will result in a scenario of a slowdown in the overall performance of the service on a reconfiguration. There is a very far possibility which will cause a drop of connections while running the reconfiguration. I will define a rule: if “squid -k parse” doesn’t take too long ( max couple secs..which is a lot for most use cases) it’s simple to assume that it won’t affect the service at all. Just take into account that the proper “ratio” of reconfiguration should be no more then once per hour and the most widely used reconfiguration is once per day. If you will want to make the service dynamic you can use external_acl and other helpers that will allow you to prevent and reconfiguration of the service when not really required. All The Bests, Eliezer Croitoru NgTech, Tech Support Mobile: +972-5-28704261 Email: <mailto:ngtech1...@gmail.com> ngtech1...@gmail.com From: squid-users On Behalf Of Manikandan Swaminathan Sent: Friday, May 6, 2022 04:33 To: squid-users@lists.squid-cache.org Subject: [squid-users] Squid Reconfigure Downtime Hello, I'm new to Squid and am currently researching the use/effects of running reconfigurations. I've come across a couple links and forums that talk about this, but since some of those are a bit dated I wanted to make sure I have the right info... We're currently running Squid 4.8, and I want to know, what is the expected downtime when running "squid -k reconfigure"? How does this affect existing and incoming connections? I ran a simple test in my machine where I reconfigure squid, while separately running multiple proxy requests. As far as I could tell, there wasn't any disruption, but I'd like to get some input from more experienced folks. Thanks, Mani ___ squid-users mailing list squid-users@lists.squid-cache.org http://lists.squid-cache.org/listinfo/squid-users