Choosing a PHP Library based on Performance

Sometimes, performance is the primary requirement when you are picking a third-party library to solve a task in your application. 

For CPU intensive work, there are often similar alternatives that you can choose from:

• Serialization with Serde, JMS Serializer or others
• Crawler Detection with jaybizzle/crawler-detect or matomo/device-detector
• Dates and Times with nesbot/carbon or cakephp/chronos

To find out which one of them is more performant for your use-case, you can set up an experiment with microtime/hr_time calls and run them against each other.

But: this provides fewer insights than running your tests directly with a Profiler such as XHProf or Tideways!

Comparing Performance of PHP Crawler Detection Libraries

For the use-case of crawler detection inside Shopware, I recently wondered which library to use when trying to detect if the current request is made by a crawler.

Naturally, you would say, let’s use PHPs native get_browser function. But there are also specialized libraries such as jaybizzle/crawler-detect or matomo/device-detector. 

Consulting their respective documentations, I came up with the following code snippet to test their speed:

I searched for different sources of example user-agents and compiled a list of roughly 2700 ones, then generated a Tideways profiling trace from the CLI for the snippet with:

tideways run php crawler.php

Here is the trace.

The result disqualifies PHPs internal get_browser because it is pretty slow. 

Both userland libraries are within 12% of each other, with 767ms vs. 685ms.

That gives me confidence that either one of them is quick enough to be used in a request testing just the one user agent of the current user.

To verify this, I generate another callgraph where each is testing the same single HTTP header and get surprised. Now matomo/device-detector is 10x slower than jaybizzle/crawler-detect.

Here is the trace.

The reason is that matomo/device-detector initializes a regular expression once, calling AbstractParser::getRegexes, which takes roughly 18ms. The actual test of the user agent against the initialized regex is quite fast. In comparison, jaybizzle/Crawler-Detect code-generates their regex as a build step.

As a result, I’d rather pick jaybizzle/crawler-detect for my use-case of detecting a crawler in a single request, as 2ms is acceptable but 20ms is already a bit too much.

This does not disqualify matomo/device-detector in general, it could primarily be used inside a background job when analyzing many user agents at the same time, so this library might not be optimized for my use-case.