Re: [OpenSTA-users] Performance testing with Open STA

[Bernie V. <Ber...@iP...>]

<Chris wrote>

> You are right there appears to be a bottleneck somewhere as the system

Monitoring CPU utilization on the servers under test (SUTs)  would be a good 
start. If you have Hyperthreading capable CPUs on the SUT(s), turn HT off 
(it distorts CPU accounting and can cause the OS to under-report CPU 
utilization by 40-50% under most workloads. This can only be done at the 
console at boot time on the servers I am familiar with).

> cannot support 5 or 10 users using the system simultaneously. The
> developers informed me that this is not a ralistic situation as there is
> no way 5 or 10 users will hit the same buttons and perform the same
> function at the same time.

Thats a prettylow number based on what you say in the following paragraph. 
But I have no idea of the system configuration, how demanding the 
transactions are, what if anything is happening on the systems you are 
testing, nor the network bandwidth between the OpenSTA load generator and 
the SUT(s). All these are worth considering and understanding to put the 
"5-10" user limit into context.

> I am currently running a test for 5 virtual users, and ramping up the
> users such that 1 user is added every 30 seconds with a 10 seconds delay
> between batches and the test is run for an hour. The recorded test takes
> about 5 minutes to run (Login, Create order Logout)for a virtual user
> and this emulates the real life situation. The problem im having now is,
> although there are no error in the application's logs, there are time
> out errors in the error log of OpenSTA, the orders appears to be
> correctly created in the database. Could this be OpenSTA timing out, I
> understand there is a timeout of 1 minute used by OpenSTA, will there be
> any effect on my application if this timeout is increased?

As a rule of thumb, I would set my ramp up period to be no less then the 
longest running script, in your case, 5 minutes. I would ignore response 
times during the ramp up and instead watch what happens to response times 
and server resource utilization (disks, network, CPU, memory,...) in the 10 
or 15 minutes following the end of the rampup period.  Also, increase the 
OpenSTA timeout to something large, say 300000 (unites are milliseconds by 
default, so this will give you up 5 minute timeout ) so you can see the true 
response times. Someone earlier on mentioned how to do that. Its a setting 
in an .ini file. Just Google OpenSTA timeout if you can't find it.

-Bernie
(www.iPerformax.com)