Re: [quicwg/base-drafts] Talk about concurrency in H3 vs. H2 (#3114)

Martin Thomson <> Tue, 22 October 2019 02:03 UTC

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Date: Mon, 21 Oct 2019 19:03:27 -0700
From: Martin Thomson <>
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Subject: Re: [quicwg/base-drafts] Talk about concurrency in H3 vs. H2 (#3114)
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martinthomson requested changes on this pull request.

I think that this isn't quite right.  It makes an unstated assumption, namely that the transport maintains a fixed "active stream count" that it uses to increment the maximum stream ID.  The decision to increase the maximum stream identifier could be made at the same point in HTTP/3 as it is in HTTP/2 if the transport+HTTP stacks were to decide that.

I think that we can stop by saying that the state machine is different and that this might result in HTTP/3 streams being regarded as closed later than in HTTP/2.  This could reduce the effective stream concurrency if the number of streams is used in a similar way to decide the maximum stream ID.

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