Cache miss stampedes

Kenner Stross kenner at
Tue Jul 31 21:32:32 UTC 2007

Yeah, good point.  I guess if you know that much about the item and its
refresh needs, then a regular out-of-band update makes more sense.

-----Original Message-----
From: Ask Bjørn Hansen [mailto:ask at] 
Sent: Tuesday, July 31, 2007 2:05 PM
To: kenner at
Cc: memcached at
Subject: Re: Cache miss stampedes

On Jul 31, 2007, at 13:17, Kenner Stross wrote:

> I've been thinking about the question of cache miss stampedes and came

> up with an idea this morning that I wanted to run by the group.
> What if, for those items that were a real "cache miss stampede" risk 
> (i.e., very-high request rate and expensive to recover from db), you 
> randomly refetched from the db regardless of whether it was in the 
> cache?  [....]

It really depends on your application.  Sometimes doing what you  
suggest works well, but often then figuring out how often to refetch  
is as much or more trouble as just having an out-of-band thing update  
the cache - and almost always much much less efficient.    If you  
have to do extra coding to make it work anyway, why make the user  
wait for it to execute?

   - ask

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