Performance impact when Dianoga OptimizingMediaCache is enabled

[kennyschreurs]

Version of Dianoga

5.1.0

Environment description

Sitecore 9.0.2 on Azure WebApp S3

What configs you have enabled

Dianoga.DisableForSites
Dianoga.Jpeg
Dianoga.Png
Dianoga.Strategy.MediaCacheAsync

What you expected to see, versus what you actually saw

When we enable Dianoga on our production environment with an empty media cache, we see the CPU and memory consumption of the Azure WebApp go up to 100%. This could be caused by the Dianoga OptimizingMediaCache adding a thread for every non optimized image to a threadpool, and the WebApp is probably suffering from thread starvation causing our site to not respond to requests. Is it possible to implement a TPL to limit the number of concurrent tasks? Instead of passing the optimization process to a threadpool an actionblock could be used to limit the performance impact.

[markgibbons25]

Nice idea with the actionblock. Not sure when I'll have time to implement this in the short term so happy to look at any PR.

(Off topic, you could look at for your prod site moving from S3 to Premium V2 / V3, for similar cost you can get better performance.)

[markgibbons25]

Fixed in 5.3.0