Transcript Welcome To
Presentation to the Rockville MDCFUG
“Load Testing Early and Often”
By Donald Doane
OpenDemand Systems
Session Overview
• Introduction to Load Testing Web Applications • Testing from Development to Deployment • Load Testing Over the LAN vs. the Internet • Creating a Real-World Example in ColdFusion • Load Testing Best Practices • Identifying Common Performance Bottlenecks • ColdFusion Performance Tuning Hints and Tips • Questions & Answers 2
OpenDemand Systems
The ColdFacts
• Most developers are familiar with the “concept” of load testing, but very few actually do it!
• Most common reasons for not testing are Time, Complexity & Cost ($$$ can be very expensive) • Most sites run into performance problems with only a few users (you don’t have to be Victoria’s Secret) • Most performance problems are discovered too late in the game to properly address the issues 3
OpenDemand Systems
What is a Load Test?
• Simulates multiple users to measure, define, validate and maintain optimal application performance, scalability and reliability • Serves as a compass for understanding the limits of any Web-enabled application and, subsequently, for managing its performance and growth 4
OpenDemand Systems
Why Load Test from Development to Deployment?
Identifies problems early on before they become costly to resolve (avoid the pyramid effect) Prevents the “Onion-Peel” syndrome Reduces development cycles Produces better quality, more scalable code Prevents revenue and credibility loss due to poor Web site performance Increases customer satisfaction and retention Enables intelligent planning for future expansion 5
OpenDemand Systems
What does it mean for your site to perform or scale well?
• Delivers page views to users in 8 seconds or less (industry standard) • Performs consistently across multiple page view requests (avoid the wack-o mole effect) • Response times scale linearly as user load increases as opposed to exponentially 6
OpenDemand Systems
Virtual User Simulation
• One-to-many relationship between user and browser requests • Browser opens multiple concurrent connections to Web server • HTTP Request-Response Thread:
GET / HTTP/1.1
Host: www.mysite.com
------------------------------ HTTP/1.1 200 OK Content-Length: 327 Content-type: text/html [BODY]
7
OpenDemand Systems Your Browser OpenLoad Appliance Virtual Users Virtual Users Your Web Site/App Virtual Users
8
OpenDemand Systems
Load Testing over the LAN vs. the Internet
LAN Testing: Eliminates network variability due to the Internet Saturates system rather than the network Internet Testing: Uncovers hidden delays due to Internet weather Exercises your pipe, routers, firewalls and load balancers in addition to the system under test Ensures Service Providers are meeting SLAs 9
OpenDemand Systems
Load Testing Do’s
Do Do test early and do test often establish what is and is not acceptable performance for your application Do test from the user’s perspective - it’s the only one that counts Do baseline and compare your findings Do monitor your system while you test Do test whenever there’s a change in your site’s content, code or infrastructure 10
OpenDemand Systems
Load Testing Don’ts
Don’t Don’t wait until the last minute to test depend on your customers to do your testing for you Don’t test under unrealistic conditions Don’t forget that increases in table sizes, disk usage and network traffic will degrade your application’s performance over time Don’t be so quick to throw hardware at the problems you turn up it doesn’t always help 11
OpenDemand Systems
Creating a Real-World Example in ColdFusion
Customer Case Study: Set up a User Profile Configure a Load Test Scenario Schedule a Load Test Analyze Test Results 12
OpenDemand Systems
13
OpenDemand Systems
14
OpenDemand Systems
15
OpenDemand Systems
16
OpenDemand Systems
17
OpenDemand Systems
18
OpenDemand Systems
19
OpenDemand Systems
20
OpenDemand Systems
21
OpenDemand Systems
22
OpenDemand Systems
23
OpenDemand Systems
24
OpenDemand Systems
25
OpenDemand Systems
26
OpenDemand Systems
27
OpenDemand Systems
28
OpenDemand Systems
29
OpenDemand Systems
30
OpenDemand Systems
31
OpenDemand Systems
Identifying Common Performance Bottlenecks
Over design of Web pages (too many graphics) Bad code (avoid recursive function calls) Web server connection limit too low (IIS is set to 10 by default) Poorly tuned Web application server (play with your Administration Server Settings) Excessive queue lengths (more than one) & wait times (more than a few milliseconds) Memory contention issues (paging in) Heavy disk I/O (high service times) Network latency (packet collisions & lost) 32
OpenDemand Systems
Performance Tuning Hints & Tips
Observe design & coding best practices (Fusebox) Pre-load images before they are needed Validate on the client whenever possible (JavaScript or ActionScript) Strip formatting white space, tabs, carriage returns and line feeds from HTML (speeds up response) Upgrade to CF5 (Up to 5x faster than CF4.5) Tune simultaneous requests per CPU (cfstat) Turn on “Trusted Cache” & increase cache size Restart server at 5-10 unresponsive requests 33
OpenDemand Systems
Performance Tuning Hints & Tips Cont’d
Log slow pages (remember 8-second rule) Enable Debugging (check processing time) Replace frequently referenced Custom Tags with User Defined Functions (less overhead) Bump up your cached query limit (if you can spare the memory) Let ColdFusion work smarter and your Database work harder (write smart SQL don’t do SELECT *) Use stored procedures for faster execution 34
OpenDemand Systems
Test your app for FREE
Register at http://www.opendemand.com/cf/ Test for up to 5 virtual users for FREE!
Try-out performance tuning tips Test again and compare results to your baseline 35
OpenDemand Systems Q&A
[email protected] http://www.opendemand.com
36