first time user with out of memory question

Stephen Woodbridge woodbri at
Sun Jun 11 17:12:04 UTC 2006


How long was your instance running?

This is similar behavior to what I started seeing after we ran the 
stress test for a while.

See the thread "Strange memcached behaivor on stress test"


Janning Vygen wrote:
> Hi
> i am running a dedicated memcached server with 4 GB Ram on linux (debian 
> stable) for php session data (kernel 2.6.8-2-k7-smp, memcached 1.1.12-1)
> Two days ago i ran "out of memory". In the log it says 
>    malloc(): Cannot allocate memory
> and stats slab produced "out of memory" message, too. At this time it was 
> impossible for many users to login to our web application.
> first i wondered because the "STAT bytes" was far lower than "STAT 
> limit_maxbytes". Then i read in the archives that memcached needs much more 
> memory than bytes to save. (60%). thats ok. i restarted memcached to get it 
> running again.
> but i am concerned about it. As i have 3,5 GB dedicated to memached (-m 3584) 
> it should not run out of memory.
> but anyway: i thought that memcached would delete the oldest key to get space 
> for a new key and you should never get an "out of memory" message as i am NOT 
> running it with -M (-M is not the default, isn't it?)
> but memcache is increasing memory since restart. Shouldn't it use old entries 
> before? I set expiration to 600 seconds but oldest entries are as old as 
> uptime:
> STAT items:8:number 38371
> STAT items:8:age 87089
> STAT uptime 87091
> Maybe i did something wrong with expiration time. But i set it to "time() + 
> 600". 
> Is it possible that memcached hit an OS limit? a look at ulimit -a shows me:
> core file size        (blocks, -c) 0
> data seg size         (kbytes, -d) unlimited
> file size             (blocks, -f) unlimited
> max locked memory     (kbytes, -l) unlimited
> max memory size       (kbytes, -m) unlimited
> open files                    (-n) 1024
> pipe size          (512 bytes, -p) 8
> stack size            (kbytes, -s) 8192
> cpu time             (seconds, -t) unlimited
> max user processes            (-u) unlimited
> virtual memory        (kbytes, -v) unlimited
> i guess i have to check this "open files" limit as this limits memcached to 
> 1024 connections, right?
> BTW: 'lsof | grep memcached' showed up some lines like this:
>   memcached 8487    root   10u  sock  0,4   54375193 can't identify protocol
> what does it mean??? Is it ok?
> Ok, long post and i didn't got to a cool question which is easy to answer. 
> Maybe somebody can give me a hint anyway. Any help is very appreciated.
> kind regards,
> janning

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