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...
> 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.reindl@stripped]
>> Sent: Tuesday, April 02, 2013 8:29 AM
>> To: mysql@stripped
>> Subject: Re: How to change max simultaneous connection parameter in
>> Am 02.04.2013 16:09, schrieb spameden:
>>> 2013/3/24 Reindl Harald <h.reindl@stripped
>>> Am 24.03.2013 05:20, schrieb spameden:
>>> > 2013/3/19 Rick James <rjames@stripped
>>> >>> 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
>> 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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