Wordpress on azure high CPU

Question

We have a WP with multiple custom modules. It is hosted on the same region on Azure web app and MySQL. From time to time(2-5 times) per month, the database CPU reaches 95% and websites go almost down. There is no any drastic change during these spikes in terms of transactions and users. Tried multiple options to debug but with now luck. Any hints?

Answer 1

As you have custom set up everything can be a culprit.

What I would check as first two things:

a) analyze your wp-cron tasks and see if any of those while running may cause the spike (you have few debug plugins allowing you to inspect WP cron).

b) analyze the wp_options table for transients which may expire like once per week and recreating them may cause high CPU load.

Answer 2

I would suggest two things: First connect your WordPress with application insight, that way you have a better chance of debugging and overview of what is happening. secondly: define a scaling rule for your CPU to combat down time.

NB: any time there is a down time, just look at the scale log and compare it with your application insight. To have a better understanding of the problem.