Load Testing Blog
Fixing: Unable to Establish Connection to the server
In this example case, we ran into a situation where a load engine could not resolve the hostname of the server being tested, even though Load Tester was able to record & replay against the server without any difficulty. This problem appears immediately, but only when running a Load Test with the troubled load engine. By using the Engines View in Load Tester, we were able to select and use each Load Engine separately in a Load Test, until the faulty engine had been isolated (this sort of problem will show errors coming back from the engine within seconds, and … Continue reading »
Custom Extractors in Web Performance Load Tester
This tutorial will outline the steps to configure a custom extractor in Load Tester. Extractors are used to recognize small pieces of data in your application and apply them to future transactions within a test case.
How-To: Recording Local Host Server
Recently we have been getting a lot of questions regarding how to use Load Tester to record against local host. While it is possible to record a local server, and may be useful for testcase development, it is however not recommended to run a load test on the same machines as the local server. Running a load test on the server can produce confusing and misleading results as well as cause resource issues. In order to get useful results, Load Tester and the web server need to be on separate machines.
In order to record against the local host; use the … Continue reading »
Web Performance Race Car Wins BMWCCA Enduro at Road Atlanta!
Jason Tower pulled off TWO first place wins in September at Road Atlanta, both in strenuous ~90 minute enduro races that push both man and car to the limit. His previous races all season have been sprints, short races where you go all out for a short period of time. Enduros require the use of some strategy and pacing since it adds refueling and pit stops into the mix. All of us here at Web Performance, Inc. are proud of the progress he’s made all season, and its now showing up in not one, but TWO first place … Continue reading »
Optimizing Drupal: From Baseline Drupal to the Pantheon Drupal Platform
Note: This is Part 2 of an ongoing series on Drupal performance and load testing. If you haven’t already, read the introduction.
Summary
We measured Drupal’s performance with a naive and recommended configuration, and again using the Pantheon Drupal Platform, demonstrating a better than 15x improvement in performance.
Procedure
We created a Drupal installation on the Amazon Elastic Cloud, which allows us to start and customize Drupal in a matter of minutes. For these tests we used Amazon’s “Large” 64bit instance, which corresponds roughly to a dual-core machine with 7.5 GB of memory.
Our baseline platform consisted of a stock Fedora Core 8 with … Continue reading »
Knowing your Security with Stress Testing
In the past, we’ve had plenty of discussion on how performance effects user experience, and how that relates to conversions. But, can a server’s performance effect it’s security?
During a previous test, we had a customer whose site included a contact form. The user would complete the contact form in their browser, and the application server would convert this response into an e-mail and send it through a mail server. The contact form, coupled with the use of a CAPTCHA, helps to cut back on undesirable messages. During our testing, we discovered that the mail server was becoming overloaded (at only … Continue reading »
Choosing the scenarios for a load test
What to test?
Occasionally, we encounter customers who have only a single scenario to test. For example, one client developed an application in which the only scenario of interest involved a user registering him/herself with the system and scheduling an appointment. When this happens, the tester may devote their efforts to the accurate simulation, testing and analysis of this single scenario. You are unlikely to be so lucky.
In any moderately complex system, there are dozens or even hundreds of scenarios that are candidates for load testing. You are not likely to have the time or resources to test them all. As … Continue reading »
Load Testing Drupal: Introduction
At Web Performance, we’re all about measuring and optimizing web applications. This quarter we decided to test a variety of Drupal configurations, starting with the most basic (unpack the drupal tarball into /var/www and run) and collecting benchmarks with increasingly sophisticated systems using optimized LAMP stacks and even a dual-server caching configuration.
For our test scenario, we imagined that we had just started a small drupal-based blog when a popular website linked to one of our stories and directed massive traffic onto our server. These visitors read stories, followed interesting links, and posted comments of their own. We … Continue reading »
The Purpose of Load Testing
Why am I doing this?
Even a well-executed Load Testing effort may fail if it does not answer the right questions…or answer them in the right way. The “right questions” might appear obvious, such as “How many hits/sec can the server handle?” Such questions, while well-intentioned, may not be the questions that really need to be answered. They may simply be the easiest questions to ask…and answer.
From a higher-level strategic level, the real questions sound something like:
1. Is this system ready to deploy?
2. Can we make this system available to another 350 users?
3. We deployed the system and the performance is … Continue reading »
Testing tip: Make it Fail
We recently had a case of debugging a testcase where Load Tester reported an error with a page that looked and appeared just as it should, except it was missing a link the user needed to move forward. Debugging this case was easy: examine the replay two pages prior to the error, and the server had added a red error message to the page indicating the selected criteria was not valid.
So why didn’t Load Tester flag this error from the server? Beneath the error message, the page was exactly identical to the expect page: form fields were present and filled … Continue reading »