memcached-1.1.12 does infinite loop

Elizabeth Mattijsen liz at
Mon May 23 03:26:00 PDT 2005

At 4:56 PM -0700 5/22/05, Brad Fitzpatrick wrote:
>A repeatable test case would be great.  Has anybody else on the list ran
>into this?

Maybe.  I've seen a memcached daemon spin for several minutes before 
coming back to live.  I've attributed it to an excessive amount of 
objects requested in a get_multi.  Since then I'm limiting to 512 
objects per get_multi and I haven't seen the problem reoccur.

This was at significanly less set cmds (max about 10/sec) and get 
cmds (max about 15/sec).

>On Sun, 22 May 2005, Andreas Vierengel wrote:
>>  hi,
>>  I was running two memcached servers for 2 weeks successfully. Each
>>  server get's about max 3000-6000 set-cmds per second and about max
>>  300-600 get-cmds per second and nearly max 1200 persistent-connections.
>>  Today both server suddenly started to infinite loop, sucking 99% cpu.
>>  I tried to strace them, but strace prints nothing, so I think it's some
>>  sort of userland-infinite-loop. Killing and restarting brought it back
>>  to work again.
>>  top says that each process had 2GB virt, 1.7GB res and 580 share. Memory
>>  consumption was constantly growing. The stats said that there were about
>>  4 billion set-cmds. About 700.000 keys are active. the values range from
>>  280-350 bytes.
>>  startup is:
>>  ulimit -n 30000
>>  memcached -u nobody -p 2000 -m 1900 -c 25000
>>  version is 1.1.12
>>  system is debian sarge with vanilla-kernel 2.6.11, 2GB RAM,
>>  dual-P4-Xeon.
>>  On my clients I get no errors, but every request was answered with undef
>>  ( I'm using perl ), pushing my database hard :)
>>  I will try several tests the next days to make it reproducible.
>>  --Andy

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