High I/O load on DNS requests

[pkarw]

What is the motivation for adding/enhancing this feature?

Original issue raised by one of the users:

I can see a lot of loooong DNS lookup on VSF API when it calls external Apis
It seems to be a know problem on NodsJS because this part runs on a monothread
So it wait for the first call to finish, if you have a lot of external API calls at the same it stays in the queue to be processed
And at a moment he cant handle it anymore and your site is unbrowsable
Its what is happening when we send a newsletter
I really would like you guys take a look at this problem because it will happen with other merchants with peak traffic

Related resources:

• https://medium.com/the-node-js-collection/what-you-should-know-to-really-understand-the-node-js-event-loop-and-its-metrics-c4907b19da4c
• dns.lookup blocks filesystem I/O nodejs/node#8436

[pkarw]

Probably a workaround is to uset etc/hosts to explicitly map the addresses however is of course not a final solution

[pkarw]

Another related article: https://stackoverflow.com/questions/51953315/docker-alpine-image-issue-with-dns-resolution-slow

[jonathanribas]

For information this issue is a Docker related environment.
One more interesting article: https://tech.xing.com/a-reason-for-unexplained-connection-timeouts-on-kubernetes-docker-abd041cf7e02

[pkarw]

https://tech.xing.com/a-reason-for-unexplained-connection-timeouts-on-kubernetes-docker-abd041cf7e02