AI - why won't you let me love you? Upgrade to new version pegs my CPU. Uninstall breaks IIS core

Question

I've been a happy consumer of the first version AI for some time. I wrestled quite a bit with it to get it to work with my code base, eventually opting out several of my namespaces in ApplicationInsights.config so that the CPU on my web servers wouldn't
go to 100%. I got it worked out with Sergey's guidance and happily enjoyed the data it provided up until now.
I recently decided to upgrade to the new Azure-based AI by installing the latest nuget package via the AI tooling in vs.net 2013 and the AI Status Monitor on my web servers. I tried a to deploy the updates last night and my nightmare has returned as my CPU
goes back to 100% for one of the servers.  
It is slightly different this time in that it only pegs one of my servers. If I bring that pegged server down, the other one pegs.
What's worse is that if I try to uninstall the AI Status Monitor it brings down my web server because it somehow corrupts Windows Process Activation Service which the WWW Publishing Service depends on. The Process Activation Service fails to start with a
'The parameter is incorrect' message. If I reinstall AI Status Monitor the process activation service and web service both start successfully. I had to leave it installed and use the AI Status Monitor interface to unregister all apps on the web server in order
to bring my prod app under control.
I don't see any documentation on the new AI.config file (the link to documentation that is added to the config file doesn't actually take you to information about the config schema) so I don't know how to opt out those same namespaces to see if I can make
the new version work. Can you provide some guidance?
One other issue - removing the NuGet package from my web projects did not remove some lines from my csproj file, specifically the <Target Name="EnsureApplicationInsightsImported"> and <Import Project="..\packages\Microsoft.ApplicationInsights.0.12.0-build17386...>
nodes.

Answer 1

Oh... These AI bugs that we know and love!... And, yet, you just pegged them :)
But, let me start from the beginning...
Last time I fell asleep I dreamt of Status Monitor causing AI Nuget server to fail on IIS start although Status monitor has been removed already... I woke up in sweat
and tears hoping for this to be just a bad dream but it turned out that the nightmare was a cruel reality and AI Nuget server could not start for real that day..
I won't forget that glorious moment when "The workaround" descended upon myself: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WAS\Environment
registry key value should be removed to make WPAS working again (although the value is empty after Status Monitor uninstall, it needs to be removed completely...)
Later, in the evening that was as dark as the mother of the nights, my silly attempts to remove AI from the web project turned into yet another buggy-like creature staring
at me from the csproj file: the mighty artifact “Leftover AI targets” (+2 to garbage in the project file) was there. It turned to be yet another known bug with a manual workaround as you can guess…
I whispered into this darkness asking teammates for the documentation but my whisper was met by nothing but a dead silence that kept me thinking that there is none and
all I have is to use web search and
AI landing page.
What happened next is even harder to imagine (though much funnier
J)… The very next morning I was trying to prove to AI team that I do not post questions on the forum under a pseudonym “J Kewley”
and I do not try to make fun of AI team that way…
Therefore, I write this to sum up our experiences and, hopefully, answer some of the questions.. The bugs are in the backlog and can make it into the next AI release, please try to work around
the problems till then.
The CPU issue is entirely separate beast, though, - the reason of such degradation should certainly be different between “old” & “new” AI.
Previous data collection logic was MMA-based and the present collection logic isn’t, so there is no namespaces to enable/disable in the new version at all.
Could you please describe the application/situation in more details to track this one down:
-   What is the application technology?
(MVC/Web API/…)
What’s the load on the application and how load is distributed across instances?
- Does w3wp.exe process consume all CPU when the issue happens or there is something else?
Maybe you can share the dump?
Dmitry Matveev