A few weeks ago we
ran an exam using our current instance of Moodle hosted on Microsoft Azura
cloud services. There were about 4,000 active test-takers during a 7 hour exam
window. Everything seemed to be going well with the test when suddenly the
system slowed down causing hundreds of people in various quizzes to experience
a significant slowdown in site responsiveness as well as a massive increase in
page loading times.
From the server side, our IT people were monitoring the situation in real time and noticed that there was a sudden massive spike in the CPU utilization assigned to the MySQL database server (a more detailed description can be found below) which seem to be the cause of the problem.
We were running 6 MCQ tests with 25 select random question from question bank quizzes. There were also essay style questions but the problem seems to coincide with increased MCQ activity.
It is 16core MySQL server
was running at over 90% plus utilization. After reviewing the data, we found
there were approximately 500 connections to the database at the time which is
very low. The memory utilization was about 20 to 30%.
We are using Moodle 3.4
Can some experts guide us, what could be the issue .
Thank you in advance for all the help