Load Testing Blog

Web Performance, Inc Boosts SHRM Website Capacity by 2,000 Percent in Time for Launch

Society for Human Resources Management website able to service its 250,000 members while introducing potential savings of $200,000.
Durham, NC – February 19, 2009 – The new Society for Human Resources Management (SHRM) website was recently given a huge capacity boost in time for its unveiling, enabling the site to handle large amounts of traffic from its 250,000 members. Web Performance, Inc., (WPI) developers of industry-leading Web Performance Load TesterTM software, increased the site’s capacity from 100 to 2000 users, and reduced server requirements to less than 25% CPU utilization, eliminating two servers altogether and reducing potential software license expenses by … Continue reading »

Virtual User Calculators

Customers frequently ask us for help deciding how many virtual users they need for their load tests. We have a number of formulas for calculating this, depending on what information the customer has available. Last weekend I built online calculators for a few of the more popular variations. Give them a try!
If these don’t apply to the data you have available, contact us and we’ll be happy to help you calculate the number of simulated users required for your specific needs!

Measuring the Performance Effects of Dynamic Compression in IIS 7.0

Enabling dynamic compression in IIS 7.0 can reduce the bandwidth usage on a particular file by up to 70%, but also reduces the maximum load a server can handle and may actually reduce site performance if the site compresses large dynamic files. Read the full report for a complete analysis.

Tutorial Comments

This is a blog post reserved for tutorial comments.  Please reference the specific tutorial when commenting.  Thanks!

Measuring the Performance Effects of mod_deflate in Apache 2.2

Enabling mod_deflate can reduce the bandwidth usage on a particular file by up to 70%, but also reduces the maximum load a server can handle and may actually reduce site performance if the site compresses large dynamic files. Read the full report for a complete analysis.

Is the last mile relevant to Load Testing?

One of our competitors has recently been emphasizing the use of their monitoring network during load tests. The pitch goes something like this: “With our last-mile monitoring network you can determine how different geographical regions will experience your web pages.” This solution has been implemented by using testing agents in the homes of real consumers to measure performance during a load test.
At first glance, this peaked our interest. However, after some analysis, we started to question the real value of this approach to load testing:

Will this approach dilute the value of the load test results?
Can the same information be obtained … Continue reading »

Load Tester improvement – better success and fail metrics

Previous versions of Load Tester had 2 metrics describing the success or failure of a web page (or single transaction) during a load test: Repeats and Errors. A Repeat was counted any time a valid HTTP response was received from the server. Errors, however, were a bit more complex. Errors could occur at any point in the transaction, from establishing a connection to post-response validation. An error was counted if the connection was terminated in the middle of a transaction. It was also counted if the status code from the server indicated a failure (e.g. a 500 status). Validators record … Continue reading »

New Load Tester feature – web page performance goals

Load Tester has supported the concept of a performance goal for quite a while, but the implementation has been rather limited. We have completed work on an improved version for our next release (3.6). Load Tester now provides the ability to set a performance goal for each web page and/or transaction in a testcase individually. Of course, you can still specify a global page performance goal, as you could in the past. In addition, users can specify a default page (or transaction) duration goal for an entire testcase and then override that value for each page or transaction. The performance … Continue reading »

Load Engine simulates 3500 users on a single PC in performance test

We are frequently asked how many load engines will be needed to run a load test. Some general guidelines are provided here. Those guidelines were established using a fairly typical test scenario. With some tuning, we were able to tune the OS and Load Engine to simulate 3500 users on a single computer.

Memory consumption and reclamation – Chrome vs. Firefox

I reboot my laptop as infrequently as possible – which means that I keep Firefox running for weeks without restarting. At least, I would prefer to. But the longer it runs, the more memory it gobbles. The only way to reclaim it is to restart.
So when I read about the tab-isolation feature in Googles new Chrome browser which uses a separate process for each tab, it peaked my interest. I installed Chrome and tried a very quick (and not very scientific) test, as described below.
Firefox had been open for a few days and currently had 8 tabs open. I am … Continue reading »

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