memcached-1.1.12 does infinite loop
Elizabeth Mattijsen
liz at dijkmat.nl
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).
Liz
==================================
>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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