"SERVER_ERROR out of memory" when changing cache entry pattern

[Alexander Zaitsev]

Hi all,

08:40:32,844 ERROR MemCachedClient:788 - ++++ error storing data in
cache for key: ip31-MRH0KvrUw82ZTkBMIm1oFA -- length: 767

I've recently got this message, though I did not expect to. I suspect it
  might be a bug in memcached.

Here is how it happened. Cache was full with more or less uniform
objects: long key and boolean value. I have switched the pattern of
cache entries that my application generates to have shorter key but few
hundred bytes value. This resulted in immediate "out of memory" on
storing any new value in the cache. Looks like memcached could not
allocate space for the bigger object than cache contained before. I.e.
it tried to release LRU entries, but it was not enough to get the
required space, because old entries were significantly smaller than new
ones.

Memcached is started as follows:
/usr/bin/memcached -m 128 -p 11211 -u root
Version 1.1.12
Debian Linux

Thanks.

-- 
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Best regards,
Alexander Zaitsev