Cache miss stampedes

[BUSTARRET, Jean-francois]

> -----Message d'origine-----
> De : dormando [mailto:dormando at rydia.net] 
> > Why not include probalistic expirations in the server ?
> >  
> 
> Not the best idea... That algorithm is completely dependent 
> on the rate of incoming requests. Memcached's options 
> (thankfully!) do not usually require on the fly tuning to work.
> 
> Putting it into the server half defeats the purpose as well. 
> The point of this game is to avoid cache misses and refresh 
> caches to avoid a stampede/dogpile/whatever.
> 
> -Dormando

You would not need tuning, and the rate of incoming requests is not a
problem IMHO.

- If the rate is very low, one can expect that there won't be any
stampede (unless the regeneration code is veeeeeeery slow, but this a
code tuning problem, and not a caching one)
- If the rate is moderate, it works fine
- If the rate is very high, I still prefer to 1% of requests
regenerating the key instead of 100% one minute later...