mc performance tuning; was: taint mode: insecure dependency in connect

Jeff McCarrell jmccarrell at
Sat Jun 14 05:41:15 UTC 2008

re: contention for memcache
Well, we don't have a very standard kind of web app.
The data show that running 8 memcaches is better for us than 1:

The graph shows the avg time to process the complete request.
The X axis shows concurrent streams of requests being sent to apache.
Each request makes several to small tens of memcache gets, and 1 multi-get.
My next set of tests will compare 8 vs 16 memcaches and scale up the number
of concurrent requests.

re: localhost:12211 vs unix domain sockets
Um, yes, I can test tcp sockets vs. unix domain sockets if there is a good
reason to.  My belief is that unix domain sockets are the fastest in
general; is there something specific to memcache that suggests otherwise?

re: multi-threaded memcache
I read about multi-threaded mc with interest.
In general, I'm leery of threading, but I would be willing to look further
into it with a little encouragement. :-)
We are running LAMP on linux 2.6 64-bit where the p is perl 5.8.5.
Is there a consensus view that memcache threading works well on that


-- jeff

On 6/12/08 12:31 AM, "dormando" <dormando at> wrote:

> contention on memcached, over localhost? That's a little bizarre.
> Can you test over localhost:11211 instead of a unix domain socket, and
> see if there's any performance difference? Multithreaded memcached
> maybe? It's pretty hard to actually contend on memcached.

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