Memcached stats items

dormando dormando at rydia.net
Wed May 21 23:40:15 UTC 2008


The 'age' is the oldest item. 'number' isn't automatically adjusted as 
items are expired, they are adjusted as they are evicted.

I'd recommend upgrading to 1.2.5, where 'stats items' gives 
per-slab-class eviction stats. You can monitor those numbers to see 
which item size is causing the most evictions (if any), and pull some 
estimates based on the rate of evictions.

It's hard / not currently possible to get the average/exact statistics 
there. They're not really all too necessary; if you're causing evictions 
either you're storing too many items with no expire time, or you're 
prematurely expiring items and need more memory, or a restart of memcached.

-Dormando

Alexander Zaitsev wrote:
> Hi all,
> 
> Could you advise how to read and understand 'stats items'? In 
> particular, I would like to know how long items live in cache (average) 
> before they are pushed out.
> For example:
> 
> stats items
> STAT items:4:number 72083
> STAT items:4:age 58041
> STAT items:5:number 89114
> STAT items:5:age 52292
> STAT items:6:number 16644
> STAT items:6:age 52224
> STAT items:7:number 89586
> STAT items:7:age 55826
> STAT items:8:number 5294
> STAT items:8:age 49658
> STAT items:9:number 16912
> STAT items:9:age 53308
> STAT items:10:number 8455
> STAT items:10:age 52034
> STAT items:11:number 9457
> STAT items:11:age 52201
> STAT items:12:number 9702
> STAT items:12:age 52394
> STAT items:13:number 11206
> STAT items:13:age 50819
> STAT items:14:number 6201
> STAT items:14:age 41512
> STAT items:15:number 3305
> STAT items:15:age 43864
> STAT items:16:number 1323
> STAT items:16:age 43923
> STAT items:17:number 704
> STAT items:17:age 57077
> STAT items:18:number 281
> STAT items:18:age 51194
> STAT items:19:number 223
> STAT items:19:age 133899
> STAT items:20:number 179
> STAT items:20:age 360707
> STAT items:21:number 64
> STAT items:21:age 505915
> STAT items:22:number 23
> STAT items:22:age 519107
> STAT items:23:number 2
> STAT items:23:age 5426
> STAT items:24:number 1
> STAT items:24:age 283914
> STAT items:25:number 1
> STAT items:25:age 818
> END
> 
> Thanks in advance!
> 



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