Re: [Sqlrelay-discussion] MySQL Load Testing

[David M. <dav...@fi...>]

It really sounds like the bottleneck is a case of clients waiting on
available connections.

The client doesn't actually log into the SQL Relay server until the
first query is run, so even if it's bottlenecked waiting on an available
connection, the client will stall out during the call to sendQuery.

When it's running slowly, take a look on the server and see if there
aren't a bunch of sqlr-listener processes.  If there are, then most of
them are holding on to client connections, waiting for an available
database connection.

You could try load testing 50 clients and see how that runs.  I'd expect
it to be fast.  Then, as you add more clients, it should slow down.  If
it follows this pattern, then the slowdown must be due to clients
waiting for available connections.  If it still runs slowly with 50 or
fewer clients, then something else is going on.

Dave

On Mon, 14 Feb 2005 09:52:21 -0000
Marvin Wright <MW...@la...> wrote:

> Hi David,
> 
> I'm having some issues while doing some load tests with sql relay.
> 
> I have a pool of 25 connections that may grow to 50 and I have
> assigned 50 cursors to the pool.
> 
> I've built a server application that uses this pool to connect to a
> local cache of data.
> 
> If I execute 1 request to my server app it returns a sub second
> response.
> 
> Now when load testing all the way to 300 concurrent requests the app
> starts returning response of upto 10 seconds.
> I've done some program tracing and filled the app with plenty of logs,
> I seem to get a bottle neck on the actual sendQuery.
> Some of these queries are taking 9 seconds to execute.  I'm also
> monitoring the database, the queries that are run are all under a
> second. The slow down seems to be somewhere in the sendQuery but
> that's all I can tell.
> 
> I thought at first that with only 50 max connections to the pool that
> the threads might be waiting for a connection but it does seem to be
> the case.
>
> If I switch access to this local cache off load-testing all the way to
> 500 connections my app will return all connections under 2 seconds.
> 
> I'm running the new pre-release version 3 of sql relay.
> 
> Any ideas what may be the problem or what I can try ?
> 
> Many thanks.
> 
> 
> Marvin Wright
> Flights Developer
> Lastminute.com
> mw...@la...
> +44 (0) 207 802 4543
> 
> 
> 
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