How to Stress Test a WordPress Website

One thing they don’t tell you about starting a blog or business site is that someday your website is going to reach its limit.

Hosting companies don’t have any interest in informing you about this, and the plugin and theme developers are simply trying to make more sales. So it’s tough to tell whether or not a plugin will conflict with your website when traffic starts increasing.

WordPress is a rather strong solution to go with, especially when you opt for a quality hosting platform. However, testing out your website before it’s live is not a realistic way to understand how your site is going to hold up.

What happens when the traffic spikes during the holidays? What about when you get a product feature on the news or in a guest blog post? Is your site ready for this type of stress?

What Do We Mean By Stress Testing?

Stress testing (or load testing) happens when you put a certain amount of stress on a software or technological system in order to test out how well if performs.

This stress testing is done in multiple environments. For example, you’ll want to see how a website loads and responds during normal traffic hours. At the same time, it’s a good idea to compare this to peak and even unusually low traffic times.

Overall, stress testing means simulating lots of users coming to your site at one time. This way you’re prepared for your success as a website owner. One thing to keep in mind is that you’re not trying to throw everything at your website at once. Seeing if your site will withstand the traffic of Facebook is useless.

Why?

Because a new website or blog won’t have the same amount of traffic as Facebook. Therefore, you need to evaluate your own numbers and figure out your average visits per day and month. Then you can take the most traffic you’ve received in a period and use that as an estimated benchmark.

However, the point of stress testing is often to anticipate for unprecedented traffic. Because of that we recommend being overly generous with your maximum number of visits.

Evaluating Your Current Performance

We recommend going to each of the following websites, pasting in your URL, then evaluating some of the frontend problems occurring:

• Pingdom
• GTMetrix
• PageSpeed Insights

Each of the sites listed above provide ratings for a multitude of factors. They also offer solutions that you may or may not be able to fix yourself. For example, a caching problem can be solved by a caching plugin, yet combining external CSS and JavaScript may take additional development knowledge.

You’ll also get some insights on how quickly your pages are loading up without much traffic at all. This can give you a good starting point for when you go through the actual stress tests.

Eliminating Problem Plugins

Seeing as how WordPress runs with plugins, there’s no doubt you’ll have at least a few of them for your WordPress install. After determining the plugins that mean the most to your website, install the P3 Profiler plugin.

Run the plugin.

It gives you a breakdown of how other plugins are affecting the speed and performance of your website. For example, you might discover that one of your most recently installed plugins conflicts with your theme and nearly brings your site to a crawl.

Although you can also manage plugins by deactivating and testing, the P3 Profiler expedites the process.

The Backend Stack

The backend is actually where most of the work is going to be done when it comes to supporting higher levels of traffic. Before you go about stress testing, you want to make sure that your backend stack is ready for the real world testing.

We suggest you cover the three following steps in order to ensure that your backend is prepared for the process:

1. Tune your stack – Everything from Apache optimization to MySQL tuning is covered here. You have quite a few different areas to think about in terms of tuning, but just keep in mind that they should all be taken care of before your stress testing.
2. Know what you’re working with – You must understand your hardware before stress testing. If you’re not familiar, have someone train you. Specs are vitally important for these types of things.
3. Document the server setup – From your PHP version to your operating system, your entire stack should be documented. These all play roles in the testing process, since logging errors become much easier.

With all of that in mind, you’re ready to start testing. The only other tip is to run your tests on a staging site (an identical one to your live site).

Load Testing: How to Do It and Which Options You Have

You have two routes to decide between when load testing. The first one involves you walking through it manually, with a DIY procedure. The other involves you choosing a commercial product for running the stress testing for you.

The DIY Route

Beginners should avoid the DIY route at all costs. However, if you consider yourself more experienced, please see if this is more up your alley.

Blazemeter has a great article with some of the most popular opensource stress testing tools. Feel free to take a look at their suggestions.

From our perspective you could technically go with anything in that article. However, we have a few favorites:

• JMeter – Here’s an opensource pure Java application, with some powerful tools for testing performance. JMeter supports tests for most major applications, servers and protocol types, and it’s a popular enough solution so that you can find documentation about it all over the internet. The program handles LAMP setups rather well, and it has a highly extensible core for things like scriptable samplers and visualization plugins.
• Siege – We like Siege because it seems about ten times easier to learn than JMeter or Tsung. It’s definitely the best bet for less experienced developers who want to give the DIY route a go. The testing and benchmarking utility simulates users, and it can eventually put the server under siege. I wouldn’t go too crazy trying to actually take down the server, but you gain access to interesting items like cookies, FTP protocols and basic authentication.

Commercial Options

For many people the DIY route is either far too intimidating or too time consuming. If you’re a less experienced developer, or you just don’t want to spend the time manually stress testing all of your sites, I recommend going with a commercial testing solution.

Keep in mind that some of these options are pricey, so your best bet is the DIY route if you have no plans to stretch your budget.

The Load Impact platform has some affordable monthly plans along with the most user friendly interface out there. Load Impact tests everything from apps to regular WordPress sites, and it has realistic, simulated users to get an idea of what people will actually be doing while on your site. This is particularly important since some users put more resources on your site than others.

Load Impact also offers a feature for loading visits from multiple different locations throughout the world. Along with serve monitoring, scenario recording and save-able user scenarios for load testing, the Load Impact tool is definitely one of a kind.

If you’re more into testing from the cloud:

Although Load Impact has some cloud tools, it’s originally created to work through the cloud and test the performance of websites and apps. The starter pricing is at $29.99 per month, and its main services include load and server performance testing.

The cool part about Blitz is that it runs automatically with the help of the Ruby GEM and Atlassian’s Bamboo CI server. Overall, it ensures that no code pushes are causing problems for your users, and it’s all done in the background. Blitz also provides Chrome and Firefox plugins, which are often nice for people with less experience.

The final commercial stress testing option is called Blazemeter. This gem takes JMeter, and some other load testers, to analyze them from locations all over the world. The platform is opensource compatible, and it provides mobile performance testing just in case you’re making an app or mobile site of some sort.

In Conclusion

The amount of stress testing you complete depends entirely on how safe you’d like to be. Generally, I recommend load testing a website at least once before setting it up for a client or launching it for your business. This way you’ve walked through a few tests to see roughly where your site might break if you reach a certain traffic load.

After that you should consider stress testing as your organization grows. Think about it: Your initial stress test might say that you’re good with up to 1,000 visits per week. Your company isn’t remotely close to that during the first year so you have nothing to worry about. But what about during the second year when your sales really start to pick up?

We suggest you commit to a yearly or bi-yearly stress testing regiment, fully understanding how much your website can take.

If you have any questions about how to stress test a WordPress website, please let us know in the comments section below.