Re: Slow connection and slow response time from memcached server

[Patrick Galbraith]

I have questions (and answers too) head wrote: any idea what might be causing the performance problem? What version of memcached are you using? I am running the newest version of memcached available, that is actually 1.4.1 What type of application/client are you using (PHP, Perl, Ruby, etc...) ? If you do a quick strace of the process, is it calling epoll_wait (and similar) or select()/poll()? I am kind of beginner admin so I am not really sure on how to do the strace, All you need to do is start memcached with "strace /usr/local/bin/memcached...". It spits out all the low level calls a binary is making. also at this moment I am unable to replicate the problem because we stopped using memcached after this problem showed up When I add memcached to my script the entire *website* I run go down in a matter of 5 minutes, if you really need this info to find my problem I will run memcached again to find out I'd have to see your script to see what the deal is :) Can you verify that yor host is not using any swap, and is not actively swapping? (watch vmstat 1 for a minute or two, the si/so columns). The host is not using any swap (zero) I am 100% positive, there is more than 6GB of ram free at the moment of a problem and cpu usage is minimal Are you using large multigets at all? I have no idea what is "multigets", care to explain? Depending on your client, you will have a "get" and a "multi get" call. "get" fetches a single item whereas "multi get" call returns multiple items (given a list of keys). For instance, Perl's Cache::Memcached client has an "mget()" and a "get_multi()" function. Finally, can you pastebin the output of "stats" and "stats settings" somewhere? (assuming you're on 1.4) I am guessing you need this for a server at the moment of performance decline, right?