Azure web app instance memory usage, high page reads/sec?

[Mark Szente]

Hello,

I have a medium Azure instance (PaaS) with 9 apps. The apps have not changed for some time. Yet, for the last-four three days, I'm getting warnings about high memory usage. Interestingly, the combined memory usage of my apps is steady, it doesn't really change. The memory usage of the whole instance hikes. As you can see, in the last day, it even made the whole instance crash multiple times.

There is a pattern in the page reads/second which is worrying, and seems to correlate with memory usage hikes. 

What's wrong? 

[#2]

It was ok for a few days, but it's happening again. Not touched the apps, and there was no significant increase in traffic.

[#3]

I'm seeing almost exactly the same pattern on one of our apps since today. Still don't understand what is going on.