memcached-1.1.12 does infinite loop

Andreas Vierengel avierengel at
Sun May 22 14:57:42 PDT 2005


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,
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.


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