Re: [Editorial Errata Reported] RFC7540 (4871)

Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com> Wed, 30 November 2016 13:54 UTC

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From: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>
Date: Wed, 30 Nov 2016 22:49:45 +0900
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To: Kazuho Oku <kazuhooku@gmail.com>
Cc: Cory Benfield <cory@lukasa.co.uk>, Martin Thomson <martin.thomson@gmail.com>, RFC Errata System <rfc-editor@rfc-editor.org>, Mike Belshe <mike@belshe.com>, Roberto Peon <fenix@google.com>, Ben Campbell <ben@nostrum.com>, Alissa Cooper <alissa@cooperw.in>, Alexey Melnikov <aamelnikov@fastmail.fm>, Patrick McManus <pmcmanus@mozilla.com>, Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
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Subject: Re: [Editorial Errata Reported] RFC7540 (4871)
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On Wed, Nov 30, 2016 at 10:29 PM, Kazuho Oku <kazuhooku@gmail.com> wrote:

> 2016-11-30 22:05 GMT+09:00 Cory Benfield <cory@lukasa.co.uk>uk>:
> >
> >
> > On 30 Nov 2016, at 13:04, Kazuho Oku <kazuhooku@gmail.com> wrote:
> >
> > My understanding is that you do not need to distinguish between
> completed, idle and blocked states.
> >
> > For a stream under either of the three states, the weight associated to
> the stream is distributed to the dependents.
> >
> > That is what nghttp2 does and H2O does (except for the fact that it does
> not remember closed streams), and I this behavior is what is suggested by
> the spec.
> >
> >
> > My understanding of what Martin is suggesting is that that isn’t true:
> blocked streams do not distribute their weight to their dependants.
>
>
> Thank you for pointing that out.
>
> My understanding is that there is no special casing for blocked
> streams. Section 5.3.1 handles all the states we are discussing
> equally, quote:
>
>    Inside the dependency tree, a dependent stream SHOULD only be
>    allocated resources if either all of the streams that it depends on
>    (the chain of parent streams up to 0x0) are closed or it is not
>    possible to make progress on them.
>
> I also do not see why it would be beneficial to treat them differently.
>
>
​I agree with Kazuho.  I think RFC 7540 is written based on the idea that
dependent stream ca​n receive resource if the streams between it and root
are all either in closed, idle or blocked.

Actually, from nghttp2 commit log, I made a commit which implemented the
proposed  text.  But we later reverted it, since there is no text in the
draft at that time to mandate that behaviour.

Best regards,
Tatsuhiro Tsujikawa




> >
> > However, that’s also what the Python Priority implementation does.
> >
> > Cory
> >
>
>
>
> --
> Kazuho Oku
>
>