Reduce HTTP/2 allocations

[davidfowl]

• Remove per request allocations on the thread pool by implementing IThreadPoolWorkItem on Http2Stream
• Made generic version of Http2Stream to store the IHttpApplication instead of using a tuple

cc @benaadams

PS: I can't run much locally, so the CI will tell me if it doesn't work 😄

[Tratcher]

Metrics?

[davidfowl]

Less allocations 😬. Honestly though I don’t have a good way to build this locally. I’ll try again but this change is better generally. Even if throughout doesn’t change.

[davidfowl]

I’ll try running something.

[davidfowl]

Also dotMemory is broken with the latest .NET Core ci builds https://github.com/dotnet/coreclr/issues/21559

[davidfowl]

Gimme a sign off bros! I tried to use Perfview but I can’t read allocations in that thing

cc @sebastienros

[sebastienros]

Honestly though I don’t have a good way to build this locally

You should add that you are in a place where internet is limited and downloading the artifacts from the CI under VPN is slow.

I will run the benchmarks for you then. I have access to the CI.

[davidfowl]

If running these benchmarks works. I'd love to show before and after allocations as well but that can wait I guess.

[halter73]

This kind of makes you wish we never made ProcessRequestsAsync a generic method and just went the generic type route to begin with.

[davidfowl]

Thanks for the conflicts @halter73

[halter73]

If anyone has advice on how to best analyze allocations using perfview, I'm interested. I got the following using the "DotNetAlloc" flag.

Before

After

It shows the JIT_ClassInitDymamicClass and JIT_New events are now longer emitted during StartStream() which is a good sign. There's still a JIT_NewArray1 remaining. I loaded symbols after taking the screenshots to confirm this is from resizing the _streams Dictionary.

I don't really know what the Inc/Exc %/Ct columns mean in the context of the "GC Heap Net Mem Stacks" view.