H2Connection never deletes old streams. about h2 HOT 2 CLOSED

I took a quick look at nghttp2's code. It seems that nghttp2 allows up to MAX_CONCURRENT_STREAMS total state, including closed streams. We should be safely able to do that.

However, we should also make sure we don't get too aggressive about missing streams. For example, we need to tolerate receiving frames for streams that we have "forgotten": in most cases we want to send RST_STREAM if that happens, though for RST_STREAM we want to just quietly accept it, and for HEADERS we want to GOAWAY (PROTOCOL_ERROR).

This is do-able, but it's a fairly large chunk of functionality. Still worth doing though.

from h2.

If we do this, we can also probably safely remove the closed streams altogether, rather than letting up to SETTINGS_MAX_CONCURRENT_STREAMS of them hang around. nghttp2 requires that for its priority implementation, but our priority implementation is going to be standalone and so will not require the information present in H2Connection.

from h2.