A performance monitoring module needs to extract information from many Drupal systems without introducing unnecessary latency or errors. I ported an existing performance monitoring module to Drupal 8 very early in the process, just a few months before DrupalCon Portland. It's been over a year since that initial release, and it's seen a staggering array of changes in response to a dozen alpha releases.

As I've developed this module I've gained a much deeper understanding of the new Drupal architecture. I'll run through the module's iterations and explain why I made certain decisions, or why I went back on others, tying it all back to what this project has taught me about Drupal 8's architecture and development process.

I'll be covering:

* Contemporary monitoring tools and strategies in Symfony and Twig
* The components in Drupal 8 that are interesting to monitor
* Building a performance-monitoring Drupal 8 module via dependency injection