performance: IIS - Sqlserver locks influence???

[Alex Callea]

Hi there,

We have a web application handling thousands of requests per seconds reading
sql server data which is heavily updated.
We are generally experiencing no performance problems.
On some occasions we get an increase of the traffic of about 15% for short
periods. In this case we observe something really strange: our webserver
CPU goes from about 40% usage to 100%, with memory usage keeping low (about
50%). We see at the same time that the number of sqlserver locks increases.
Are these 2 behaviours correlated? ..or any other ideas?
We are using w2k and sql2K

Thanks for your help

Alex

 

[John Saunders]

Hi there,

We have a web application handling thousands of requests per seconds
reading sql server data which is heavily updated.
We are generally experiencing no performance problems.
On some occasions we get an increase of the traffic of about 15% for short
periods. In this case we observe something really strange: our webserver
CPU goes from about 40% usage to 100%, with memory usage keeping low
(about 50%). We see at the same time that the number of sqlserver locks
increases.
Are these 2 behaviours correlated? ..or any other ideas?

The traffic increases by 15%. The traffic passes through IIS. The
application in IIS calls SQL Server.

If I'm right, then this suggests that the behaviors correlate.

John Saunders

 

[Alex Callea]

I know it's correlated but my question was to know if the increase number of
locks had cpu usage consequences on IIS.

We already noticed that the number of web requests being processed has huge
impact on webservers CPUs.
I'd like to know if the same apply with SQL locks(e.g. ADO.NET objects need
to wait more resulting in an increase of page processing time, etc...) as
the SQL server CPUs are almost not impacted by the increased traffic.
Thanks

Alex

 

[John Saunders]

I know it's correlated but my question was to know if the increase number
of locks had cpu usage consequences on IIS.

We already noticed that the number of web requests being processed has
huge impact on webservers CPUs.
I'd like to know if the same apply with SQL locks(e.g. ADO.NET objects
need to wait more resulting in an increase of page processing time,
etc...) as the SQL server CPUs are almost not impacted by the increased
traffic.

Alex, I am certainly not an expert on IIS performance, but I can't think why
it would in any way be affected by SQL Server locks.

John

 

[David Browne]

Alex, I am certainly not an expert on IIS performance, but I can't think
why it would in any way be affected by SQL Server locks.

The relationship is probably indirect. Sql Server locks are a directly
related to the volume of work being done by Sql Server. Locks don't
indicate that clients are waiting, just that they are doing stuff. Reading
tables generates shared locks, updating tables generates update or exclusive
locks, etc. So the more work, the more locks.

David