[dev] shares performance hit (was Re: disable shares)

[Didi Rieder]

Quoting duck at obala.net:

> Quoting "Didi Rieder" <adrieder at sbox.tugraz.at>:
>
>>> Said that. You should get more from your server. 12 seconds to check
>>> only 13k rows is definitely too much for a server you mentioned. I
>>> have 13,465 rows in Kronolith shares and a query like that takes onl
>>> 0.2254 sec! For Ansel Shares where I have 67.888 galleries in it,
>>> takes only 1.9356 sec!
>>
>> The query was slow when our public computer rooms are getting filled
>> by students and people/employees start to work.
>> When I do it at later times when most of the users are already logged
>> on, then it also takes ~0.08 sec. But I'll see what I can do for
>> improving this.
>
> This indicates that maybe shares queries are not all the problem if
> perform well after login. The can be a lot of small queries that are
> not visible in the log. Do you check the processes in real time? You
> can do it easily wit the mytop utility
> (http://jeremy.zawodny.com/mysql/mytop/).
>
> How many mysql threads do you run?
> What driver do you use for session and cache?
> Do you pre-warm your cache?
>

Well now (2 PM) there are about 1,000 active user sessions, mysql is  
running with 10-20 threads. mytop shows that almost all the vislible  
queries shares queries. I the moment when the machine produced the  
slow queries hundreds of threads were running. I also noticed that I  
have to increase the max number of allowed open files.

I'm using memcached (one on each of the 4 webservers) as cache and  
session driver. How would you prewarm it?

Didi

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Didi Rieder
adrieder at sbox.tugraz.at
PGPKey ID: 3431D0B0
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