Use zero byte reads for incoming TLS frames

[davidfowl]

• We recently did some work to reduce the amount of memory allocated by SslStream on idle reads so take advantage of it here by using a new StreamPipeReader feature that makes zero byte reads on the underlying Stream.

You can see some of that work here:

• Reduce memory usage by SSLStream runtime#49019
• Reduce the size of the pipe runtime#49270
• Add an option to do zero byte reads on StreamPipeReader runtime#49117

The scenario is 5000 connections sending websocket pings from both server and client:
These are GC Heap sizes:

5000 NO TLS - 68,967,016 B

Before:

5000 TLS - 310,459,272 B

After:

5000 TLS - 119,175,792

SslStream is still holding onto a 4K buffer but this is a big improvement. I want to get it much closer to the non-TLS connections.

cc @geoffkizer @stephentoub @wfurt

[stephentoub]

Glad to see this having the desired effect.

Should this in some way respect the WaitForDataBeforeAllocatingBuffer setting at the transport layer? Or if not because it's the wrong layer, if such a setting was important there, is one important here?

[davidfowl]

Should this in some way respect the WaitForDataBeforeAllocatingBuffer setting at the transport layer? Or if not because it's the wrong layer, if such a setting was important there, is one important here?

Definitely possible to respect this setting but it would need more public API to flow the setting via a feature as part of the transport layer or have an https specific setting (it'd be a layering violation to flow this existing setting directly into kestrel). I didn't want to do either as part of this PR because it requires a new API and I didn't measure any performance difference is basic scenarios.

[davidfowl]

I filed this to consider adding a new API #30877.

[geoffkizer]

Great to see this validate the SslStream work.

[ghost]

Hi @geoffkizer. It looks like you just commented on a closed PR. The team will most probably miss it. If you'd like to bring something important up to their attention, consider filing a new issue and add enough details to build context.