Load Testing ASP.Net Applications for Scalability and Performance

with Richard Campbell

Definitions

·GC - Garbage Collection

·WAST - Windows application stress tool

·RTT - Round Trip Time

Load Failure

·Looks like a bug

• Object reference not found
• Usually in relation to Session

·If the GC is too slow, the process will reset

What eats memory

·Session is long duration memory

·Cached objects

• The server will destroy the cache if needed

Where to start

·Get one good script

·What is the most common usage/path

·Build scripts from WebTrends

How to test

·You can test in VM

·Run for 2 - 3 hours for more realistic data

What to look for

·Heap size

·Request caches

Performance

·Concurrent Users are different than Active users

·Pages per Second is different than Transaction Per Second

·RTT can be a killer

·ASP.Net will tend to die due to memory first

Performance versus Scaling

·Scaling is the difference in performance between the best and the worst performance

Tools

·StrangeLoop - performance enhancement hardware

·VSTS for Software Testers

o Can cluster multiple machines together

o Provides a variety of measures

·Perfmon

·YSlow for Firefox

·Apdex.org - Application Performance Index

Notes

·Every product is load tested

• Either in a lab or with your customers

·Performance testing must be a day 1 actility

·Processors are either on or off. 80% means it's on 80% of the time

·Average web page is 250k with 60 resources