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 »
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 »
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 »
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 »
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 »
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 »
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 »
When I first started writing test cases with Load Tester, I found it easy to fall into the psychological trap of writing functional test cases. But load testing requires a different approach, and inadequate tests can cost you time and money.
Functional test cases (such as the unit tests popularized by JUnit) confirm the correctness of a system. These tests should be highly specific and have excellent code coverage. A good engineer approaches functional testing as though she were designing a jet engine: if any screw, flange, or circuit fails then the entire system is completely … Continue reading »
There are a few errors that are frequently reported by customers. One of them being the missing user variables error. A missing user variables error basically means that a variable that was suppose to be extracted on an earlier page was not extracted, and the user is now trying to use that variable. The error can be caused by a number of things, the most common are server connectivity issues and improper configuration of a dynamic value.
If the missing user variable error was caused by server connectivity issues, there tends to be a server error before … Continue reading »
We’ve seen that modern browsers have made great strides to improve efficiency in rendering and javascript performance. But, the differences seem to be less noticeable when the network is stubborn. On a recent trip, I ran into just this problem. During the evening, the hotel’s local Wi-Fi seemed at peak capacity, the DNS servers were sluggish, and just getting connections opened often added a couple seconds. Getting onto common sites like Slashdot seemed to take 30 seconds or more from the overburdened local connection.
This seemed like a golden opportunity to try out one of Opera’s new features: Opera … Continue reading »
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