Debugging TCP/IP Port Exhaustion in an Azure WebApp
This could possibly be solved by updating your Ravendb instance! Read more here:https://ayende.com/blog/173057/production-postmorterm-houston-we-have-a-problem.
From changelog, release 3.0.30100:
Fixed UDP port leak in licensing component
also this, from 3.0.30115:
[Major] [Prefetching] Fixed memory leak that could lead into slowness of the server under heavy load impacting indexing and replication mechanisms
And some useful knowledge on Azure services and availability of ports: http://www.freekpaans.nl/2015/08/starving-outgoing-connections-on-windows-azure-web-sites/
In short, the issues goes for async calls where the UDP reply packet for whatever reason is dropped/lost. Before the issue was solved, this would mean an async call that keeps listening for the response until e.g. a crash or iisreset.
We are rolling out the upgrade to try to fix our instance of the same issue within the next 24 hours, but I thought I would reply right away, so you might be able to test too if this is indeed your problem.
I will get back to this post to confirm that the issue will go away - only way to know for sure is to update Ravendb and wait and see for a week or two.