Expiration Behavior

ydnar ydnar at shaderlab.com
Tue May 8 18:05:55 UTC 2007

Would it be possible to force a discard of the LRU on all inserts,  
regardless of memory used if the LRU is expired?

If your dataset to cache is "only" 10GB, and expires after 1 hour,  
then on a 30GB memcached install it would only use ~10GB of memory,  
rather than all 30GB with ~20GB of stale data. Is that a fair  


On May 8, 2007, at 10:56 AM, Jehiah Czebotar wrote:

> On 5/8/07, Timo Ewalds <timo at tzc.com> wrote:
>> As a point of interest, a reaper command could be useful. It is not
>> something we would ever run while our site is live, but, if we're  
>> taking
>> the site down to do a code update, and likely flushing or restarting
>> memcache anyway, the time it takes to run wouldn't matter, and it  
>> would
>> be a great way to see how much memcache space we really need. We're
>> getting a 95% hit rate with our 30gb, but, would 10gb be enough? With
>> the latest version we will be able to tell if we're getting any
>> evictions, but that just tells us if we don't have enough space,  
>> not if
>> we've got way too much.
> There was talk of adding a new statistic to capture information about
> the number of items pushed from cache before their expiration time;
> that would also give you the same information.
> I'm not sure if there was a patch for that, or if it is in the  
> current release.
> --
> jehiah

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