memcached replication

Ben Manes ben_manes at
Fri Aug 31 23:12:31 UTC 2007

I just finished rewriting our caching layer, and this is exactly what we did - ehcache backed by memcached.  When invalidation occurs, the remote cache is rewarmed and a JMS message is broadcasted for all servers to refresh their caches.  There's a lot more whiz-bang features, of course, and it performs pretty darn well.  It takes about 5-10 minutes to convert a new cache based on ehcache over to one that is also backed by memcached and participates in all the cache management flows.

----- Original Message ----
From: Matt Ingenthron <Matt.Ingenthron at Sun.COM>
To: Marcus Bointon <marcus at>
Cc: Memcached list <memcached at>
Sent: Tuesday, August 28, 2007 10:31:28 PM
Subject: Re: memcached replication

Marcus Bointon wrote:
> On 29 Aug 2007, at 00:37, Dustin Sallings wrote:
>> My goal is not replication, but to allow for a sort of L1 cache in an 
>> application with memcached as an L2 and cache invalidation service.
> That's a really nice idea. I've seen something vaguely similar with 
> jgroups, but it lacks the best bits of both memcache and in-process 
> caches (I'm also using APC with PHP). I can see that being a very 
> efficient system.

That's also what ehCache does (in process cache, with remote L2 cache) 
for Java applications. 

I've looked at it a bit and talked with Greg Luck about it (the night he 
released his "benchmark" between ehCache and memcached).  The 
"benchmark" shows an impressive chart but leaves out the details you 
really need to understand what's going on-- looks like his blog filled 
in the details.

Personally, I see room for both approaches.  From discussions with 
others, there are times you just want an app to minimize local memory 
usage.  Plus, in talking with Greg, he specifically plans in most cases 
to have a cache that overflows OS page buffer, which tells you it's 
typically deployed in a different way than memcached.  That doesn't 
negate the fact that sometimes a well managed, in-process cache would be 
an advantage.

- Matt

Matt Ingenthron - Web Infrastructure Solutions Architect
Sun Microsystems, Inc. - Global Systems Practice
email: matt.ingenthron at             Phone: 310-242-6439

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