Am 02.04.2013 23:14, schrieb Rick James: > (Thanks for the comment, spameden.) > Well, I was going to drop the thread, but he baited me. I _do_ know > something about web serving...
maybe > Should I recount the number of times I have traced a database meltdown back > to MaxClients being too big? They are _ugly_ meltdowns -- hundreds of > point-queries stumbling over themselves, flooding the slowlog with queries > that should never take more than milliseconds. More and more db requests > come in, non finishing, thereby stalling the web server threads, etc. been there, done that it is a matter of the application design to avoid deadlocks in such cases > Another point to make -- once a web server (Apache or...) has saturated the > CPU (or other shared resource), there is really no advantage, only > disadvantage, in starting more web pages. The will simply contend for the > saturated resource, thereby slowing down _all_ threads. It is better (at > this point) to queue up (or drop) further requests, thereby giving the CPU a > chance to actually finish something. but with 20-100 requests a webserver these days is NOT saturated MaxClients 20 is laughable i had a high trafic site with MaxClients set to 500, driven with our CMS-system teh CPU load was at 80% and the page got damned slow because you have to wait before your images could be loaded after raise MacClients to 600 it ran smooth, the CPU was around 85% again: 20-100 MaxClients is laughable and only suiteable for a dedicated, low-powered machine hosting only one domain > Yet another point... If > [ SUM(MaxClients) over the web servers you have ] > > [ SUM(max_connections) over the Slaves ], > then you are threatening to have mysql refuse connections no, my db-layer is traing again for some times and the chance to get a free slot because other workers are serving images is proven in practice damned high > >> -----Original Message----- >> From: Reindl Harald [mailto:h.rei...@thelounge.net] >> Sent: Tuesday, April 02, 2013 8:29 AM >> To: mysql@lists.mysql.com >> Subject: Re: How to change max simultaneous connection parameter in >> mysql. >> >> >> >> Am 02.04.2013 16:09, schrieb spameden: >>> 2013/3/24 Reindl Harald <h.rei...@thelounge.net >>> <mailto:h.rei...@thelounge.net>> >>> >>> Am 24.03.2013 05:20, schrieb spameden: >>> > 2013/3/19 Rick James <rja...@yahoo-inc.com >> <mailto:rja...@yahoo-inc.com>>: >>> >>> you never have hosted a large site >>> >> Check my email address before saying that. >>> > >>> > :D >>> >>> as said, big company does not have only geniusses >>> >>> I do not judge only on 1 parameter, Rick has been constantly helping >>> here and I'm pretty sure he has more knowledge on MySQL than you. >> >> but the MySQL knowledge alone is not enough in context of a webserver >> not to say irrelevant >> >>> >> 20 may be low, but 100 is rather high. >>> > Never use apache2 it has so many problems under load.. >>> >>> if you are too supid to configure it yes >>> >>> Ever heard about Slow HTTP DoS attack? >> >> my config says yes as i heard about many things because it is my daily >> job >> >> 0 0 LOG tcp -- eth0 * !<local-network>/24 >> 0.0.0.0/0 multiport dports >> 80,443 tcpflags: 0x17/0x02 #conn src/32 > 50 limit: avg 100/hour burst >> 5 LOG flags 0 level 7 prefix "Firewall >> Slowloris: " >> 0 0 DROP tcp -- eth0 * !<local-network>/24 >> 0.0.0.0/0 multiport dports >> 80,443 tcpflags: 0x17/0x02 #conn src/32 > 50
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