startMode="AlwaysRunning" for inProcess ANCM

[shirhatti]

There was an earlier issue asking for this (aspnet/AspNetCoreModule#29) which we declined to do when ANCM was only out of process.

At the minimum, we need to ensure ANCM doesn't break with AlwaysRunning for 2,1. I suspect it might just work, but @jkotalik and @pan-wang know better.

[pan-wang]

AlwaysRunning just let WAS start w3wp.exe. Customer's true ask is about "Application_Start" or a "Startup" class in asp.Net core. I don't think asp.net core emit such notification. @davidfowl @Tratcher can you confirm it?

[asbjornu]

I'm with @pan-wang in that the requirement here might be two or even threefold. Solving the IIS worker process recycle mechanism isn't a real solution, at least not to me. Microsoft has managed to make this very complicated and hard to understand by having three different related and similar features for "keeping an IIS application warm" (which I believe is what most developers want):

1. Implementing the IProcessHostPreloadClient interface and registering it within the serviceAutoStartProviders section of IIS.
2. Configure the AutoStart feature.
3. Install and configure the applicationInitialization IIS module.

I think the first requires the second point, but I have no idea how they interact with the third. Why this has to be so difficult is impossible for me to understand, but I believe the feature request is as simple as: Please give us a way to control how our ASP.NET Core web applications are recycled and when they are, make IIS perform an HTTP request to it so the application can warm itself up.

[tuespetre]

@shirhatti @asbjornu my original request was basically this: when the application pool starts I want the app to also start. I don’t want it to wait for a request to start.

[sergioadh]

I participated in the previous thread and I was asking for what @tuespetre said as well

[shirhatti]

my original request was basically this: when the application pool starts I want the app to also start. I don’t want it to wait for a request to start.

Yup, we're on the same page here. Forgive my rather ambiguous issue title

[Looooooka]

https://blogs.msdn.microsoft.com/benjaminperkins/2014/01/07/configure-the-iis-application-initialization-module/
this works for me

[jkotalik]

I think we need to keep the current AlwaysRunning functionality the same as before. If we want to support "when the application pool starts I want the app to also start," we should design a different feature. For example, @BillHiebert wanted to use "AlwaysRunning" to allow VS to debug attach to w3wp.exe before the first request comes in.

[shirhatti]

I disagree. The semantic meaning of the feature is not just to start w3wp.exe, but rather start your application as well. This is what happens with a system.web app today.
Just because we got we never got around to doing it in ANCM thus far, we don't have to preserve that status quo.

Designing it is a new feature is not a viable option since we can't modify IIS schema to add another attribute to the AppPool.

[jkotalik]

Will this be any different from the app warmup module https://blogs.msdn.microsoft.com/bryang/2011/04/29/iis-application-warm-up-module/ ?

[rockerinthelocker]

This thread is somewhat confusing because IIS Application Initialization already works well with ASP.NET Core (via startMode="AlwaysRunning" and preloadEnabled="true" settings) to 'warm up' an ASP.NET Core application (i.e. via 'Configure' method). Can anyone shed some light on this? Thank you!

[sergioadh]

AlwaysRunning and preloadEnabled control the application pool but not the ASP.NET Core app, which shuts down somehow. Even though the app pool is "warmed-up" the first requests will take a long time since the ASP.NET Core app is not "warmed-up".

There were previous issues and this has been moved around but you can read them:

aspnet/AspNetCoreModule#29

aspnet/IISIntegration#161

[tuespetre]

@jkotalik @rockerinthelocker:

The difference between this proposed feature and using the warmup/initialization module is that this proposed feature would not require a 'sentinel' web request to be issued to kick off the application. Additionally, when an application running under ANCM 'crashes', ANCM will simply wait until another request is issued to start up the application again. This is fundamentally disconnected from the application pool lifecycle, and thus the initialization module.

[rockerinthelocker]

@sergioadh , Well, it's up to the application developer to implement 'warm up' tasks to be executed on application start. There is no magic the ASP.NET Core module can do for developers.

@tuespetre , If it were possible to implement such a feature, no hosting provider would install the ASP.NET Core module on shared servers. Just imagine thousands of sites hosted on a server would 'warm up' on each IIS start/reset/configuration change.

[Looooooka]

I really don't see what the problem is here. The module literally allows you to set a start url which is called when the pool is started. All you need to do is handle it and preload whatever you want.

[sergioadh]

That's ok and good but the Kestrel server goes down even though the ApplicationPool is up, so when the app pool recycles it will send the request and we can get everything up and running but then Kestrel goes down and if a request comes in it takes a while to respond.