Memcache not freeing memory when a key expires

Stephen Corgiat nitelord at
Mon Feb 27 23:01:58 UTC 2006


We're seeing some weird behavior from memcached.. Hopefully somebody can
provide some knowledge on this issue.

When we set a key in memcache with a TTL of, say, 60 seconds, after 60
seconds has gone by the data "expires".  This is normal, but it seems the
data is not truely freed by memcached (based on the 'bytes' stats field).
We've found that the only way to get the memory released is to try to do a
GET on the key.

I always thought if you had a bunch of keys with a TTL of 0, once all
available memory was consumed, memcache would start removing the least used
keys to make room for new keys. In our tests, this never happened.

We've tried installations on FreeBSD & Linux, 1.1.12 & 1.1.11... all with
the same results.

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