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Re: RFC: Pausing a query thread


My understanding is that Rackspace Cloud MySQL uses Virtuozzo to control IO per user.


On Mon, 6/24/13, Roberto Spadim <roberto@xxxxxxxxxxxxx> wrote:

 Subject: Re: [Maria-developers] RFC: Pausing a query thread
 To: "Peter Laursen" <peter_laursen@xxxxxxxxxx>
 Cc: "Sergei Golubchik" <serg@xxxxxxxxxxx>, "maria-developers@xxxxxxxxxxxxxxxxxxx" <maria-developers@xxxxxxxxxxxxxxxxxxx>
 Date: Monday, June 24, 2013, 1:56 PM
 hi Peter, i was helping some
 guys in a datacenter here in brazil and they implement
 server hosting via virtual machines, in other words, they
 have a very big linux cluster and many virtual machines with
 memory/cpu restrictions, maybe that's the solution they
 give... in each virtual machine they run a 'small
 server', it's a very 'expensive' solution,
 but works... a cheaper one could be a per process
 restriction via variables tunes / os restrictions
 there's some others mysql patchs
 (github lauchpad others) that limit mysql resources, but i
 didn't used 
 ---getting back to your idea: "SET
 PRIOTITY = xxxx FOR processlist.id=xxxx"
 what this should do? change 'nice'
 value of linux pid? it can help, but i tryed this some times
 and when problem is disk i/o limit it don't
 'solve' the problem, just help
 i see a better solution using the MDEV-4623 that i told,
 and this others MDEVs (MDEV-4615 -
 vertical partitioning, MDEV-3932 -
 mysql 5.6 merge) with vetical/horizontal partitioning and
 partition lock prunes
 with vertical/horizontal partitioning +
 partition lock prunes, we can "change" a myisam
 table with table lock level, to a myisam table with
 'partition lock' level, and implement a good
 partitioning that help us to minimize the lock contention,
 and after we can change query cache to prune partitions too,
 giving a better query cache hit rate (MDEV-4676)
 any other idea? maybe after this mdevs
 an script could 'optimize' server 'online'
 reading query cache queries removing some queries, reading
 processlist and locking/unlocking some process and any other
 my ideas was added in mariadb JIRA but i
 don't know if this solve your problem and when someone
 will start development, i don't know many things about
 mariadb source code, and i can't develop it (not yet =],
 but maybe in future i can), if you want to vote that mdev we
 can have a better rank position in JIRA and maybe someone
 give more priority to this and help us developing
 any other ideas? i have the same problem
 for many queries, but in my case i can change source code of
 some projects, others projects i just tell developers to
 rewrite queries and optimize to better performace
 sorry my english errors that's
 not my main language. 
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