Best Java client ?

Dustin Sallings dustin at
Fri May 9 16:08:04 UTC 2008

On May 9, 2008, at 4:54, Henrik Schröder wrote:

> Out of pure curiosity, have you benchmarked the difference between  
> your single-connection client and a comparable multi-connection one  
> with a connection pool?

	I've done various small benchmarks and profiling, but I've not done  
massively large-scale testing.  I don't have a lot of computer  
hardware to throw at a test cluster at the moment.

	I've been planning on building some test plans against EC2, but other  
than availability zones, I don't have much control over the network,  
so it might be able to show me when something is bad, but I don't  
expect it to show me when something is good.

> And have I understood it correctly that the reason your version is  
> as fast as or faster than a multi-connection one because memcached  
> in itself is single-threaded and will process requests in a  
> serialized fashion anyway?

	That was the initial idea, yeah.  I had a branch a while back that  
would run over multiple connections, but I didn't notice much of a  
difference -- again within the hardware I had available at the time.

	What I have seen is that the IO thread can saturate a CPU well before  
it saturates the network interface.  There are a couple of reasons for  
this, the biggest being that decompression and deserialization are  
both processed as part of the IO thread.  I'm hoping to find a good  
solution to this problem first (one that doesn't require me to  
reimplement HashMap anyway, although it may come down to that).

	So the next thing is to fire up multiple IO threads.  Some users do  
this already by just having more than one client instance.  While this  
isn't a particularly terrible hack, I'm hoping that I can make  
something a bit more convenient here.

Dustin Sallings

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