Speed difference under load

[Mikael Johansson]

Hi,

The default connection timeout in pecl/memcache is 1 second, and when
using Memcache::addServer() the connection isn't established until the
first command is sent (ie. the "get" in your example). Perhaps you have
added several servers, one of which is unreachable, and thus the client
will stall 1 second before flagging that server as down and trying the
next one. If you're using persistent connections, that server will still
be flagged as down on subsequent requests and will be skipped immediately.

Or as Marc said, the client might indeed be waiting for a DNS response..

//Mikael

K J wrote:
>     The slowdown is almost certainly in your client library. The server, on
>     our systems, takes about 1.5 milliseconds to start up, and a
>     fraction of
>     a millisecond to answer the first request. But your client might be
>     doing a lot of work the first time it executes. You didn't say what your
>     client language and environment is, so it's kind of hard to even take a
>     useful guess.
> 
>  
> The app is running on PHP and is using the PHP memcache library:
> http://cn2.php.net/manual/en/ref.memcache.php
>  
> I record the time it takes to render a page, and every page ends up
> taking 1 second or so.  Most of that 1 second is due to the very first
> memcache get request.  It happens at every page that uses memcache.  The
> only time this problem goes away is when I run a load testing tool and
> start having multiple users hit the system constantly.
>  
> 
> 
>  
> On 10/27/07, *Steven Grimm* <sgrimm at facebook.com
> <mailto:sgrimm at facebook.com>> wrote:
> 
>     K J wrote:
>     > So it's normal to have Memcache's response time be 1 second, if the
>     > system is relatively idle?  This happens when I'm basically the only
>     > user on the system, logging in, checking pages, etc.
> 
>     The slowdown is almost certainly in your client library. The server, on
>     our systems, takes about 1.5 milliseconds to start up, and a fraction of
>     a millisecond to answer the first request. But your client might be
>     doing a lot of work the first time it executes. You didn't say what your
>     client language and environment is, so it's kind of hard to even take a
>     useful guess.
> 
>     -Steve
> 
> 

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