Well, after some thinking on the problem, I'm thinking on sticking to the standard method, we do not expect a lot of movement of instances. I just didn't expect such a overhead when using the consistent method, so I wondered if something is wrong.
On 27 Фев, 17:07, Boris Partensky <[email protected]> wrote: > Also not related, just curious: why did you feel the need to switch to > consistent hashing? Did the memcached instances go down/get restarted a lot > or did you just feel that it was the right thing to do since you are > anticipating more instances added? > > Boris > > 2009/2/27 Pavel Aleksandrov <[email protected]> > > > > > > > Never mind the PHP, it's a topic I don't want to discuss :) > > > About the changes - the only change that made this impact was changing > > the hash distribution method. We are currently using the new memcache > > instances, but with the standard, naive method and there are no > > negative effects on the load of the web nodes. The moment we switch to > > the consistent method the load jumps. > > > On 27 Фев, 16:53, Brian Moon <[email protected]> wrote: > > > On 2/27/09 8:50 AM, Pavel Aleksandrov wrote: > > > > > Hello, I am working for a big web site. We have around 9000 hits/s on > > > > our MySQL replication trees and 500 000 unique visitors each day, just > > > > to give a clue about the load we are experiencing. We run on MySQL, > > > > Apache2, Gentoo, PHP 4 + PECL Memcache module. We've been using a > > > > single 12G memcached instance for speeding up things (we've reached > > > > the point where we can't solely rely on our DB). Using a single > > > > instance is not what memcached is meant for, so we decided to scale > > > > things up a bit, so we added 12 more instances, 2G each (32 bit > > > > servers, 4 instances per server, 3 servers). Then we switched from the > > > > "standard" (naive) method of hash distribution to the "consistent" > > > > method. > > > > > What happened was that the load on our web nodes (we have 3 of them) > > > > went up about 3 times the usual. I'm guessing it's the new hash > > > > distribution method that's doing this. Am I missing something or using > > > > this method is always so CPU intensive? Do we have another choice or > > > > we should invest in more web nodes, to distribute the new load if we > > > > decide to stick to the consistent hashing algorithm? > > > > Are you really using PHP4? Not related just shocked. > > > > Did you make all these changes at once? > > > > -- > > > > Brian. > > -- > --Boris
