Michael Nygard, author of Release It!, writes about software architecture, service design, stability patterns, and how development practice is changing.
Commenters recommend his book Release It! and link his posts on services by lifecycle, the fear cycle, and the future of software development.
If you are writing server software, I recommend Michael Nygard's book "Release It!: Design and Deploy Production-Ready Software". Measuring event loop lag sounds like Nygard's "Circuit Breaker" pattern to avoid cascading failures.
The book's examples and text are all Java, but the lessons are applicable anywhere. He offers many scalability patterns (resource pools) and anti-patterns (runaway log files) with interesting stories from his experience debugging real systems. I especially liked his story about debugging a crash in an Oracle DB driver that caused unexpected Java exceptions to be thrown from java.sql.Statement.close(), which quickly blocked a DB connection pool.
http://michaelnygard.com/
This is now reminding me of this blog I found on HN yesterday:
http://www.michaelnygard.com/blog/2015/07/the-fear-cycle/
Once you have enough sewer/natural gas/electric/cable/telephone/fiber/water/who knows what else/ lines buried under the streets I can totally understand how nobody would want to touch that with a ten foot pole, just like legacy code :)
Also read this:
http://www.michaelnygard.com/blog/2009/02/fast_iteration_versus_elegant.html
Fast iteration wins. OpenStack is far ahead in this regard and only picking up speed.
Also references another interesting article about a stateful service design antipatter: https://www.michaelnygard.com/blog/2018/01/services-by-lifecycle/
Some information at:
http://www.michaelnygard.com/blog/2010/04/the_future_of_software_develop.html
"The Future of Software Development"