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Re: #38 - HTTP2 min value for server supported max_concurrent_streams

From: Patrick McManus <pmcmanus@mozilla.com>
Date: Sat, 23 Feb 2013 15:49:15 -0500
Message-ID: <CAOdDvNqxfqn+jQNsKO4teaXreBUyf3+tJjj6oTB_1nEdOJLM4A@mail.gmail.com>
To: Osama Mazahir <OSAMAM@microsoft.com>
Cc: "ietf-http-wg@w3.org Group" <ietf-http-wg@w3.org>
8 is simply way too low for today's internet subresource count.. and
we can't rely on the main resource (html) round trip to establish the
setting as subresources are often served from a different host (e.g. a
cdn).

the guiding metric shouldn't be http/1 conns-per-hostname (6) but
rather the realistic conns-per-page we see with sharding. Which is
MUCH higher.

The default should be at least on the order of 100 (as I believe it
currently is), but honestly with the newer flow control measures in
place should perhaps be even higher to let the parallelism and
prioritization mechanisms work unobstructed.

On Fri, Feb 22, 2013 at 12:00 AM, Osama Mazahir <OSAMAM@microsoft.com> wrote:
> Hi,
>
> Issue #38 [1] tracks:
>         (1) What is the minimum number of concurrent client-initiated streams that a server must be able to support?
>         (2) What is the default value?
>
> We have a race condition where the client can initiate more streams to the server before the server can advertise its stream accept limit to the client.  I suggest making the default the same as the minimum so that we can prevent that race.  And tighten the wording on what is legal.  For example, something like:
>
> A server MUST be able to handle at least 8 concurrent streams initiated by the client. A server MUST NOT advertise a value less than 8. A client MUST generate a session error if it receives a value less than 8 from the server. The default value server limit is 8.
>
> Thanks,
> --Osama.
>
> [1] https://github.com/http2/http2-spec/issues/38
>
>


On Fri, Feb 22, 2013 at 12:00 AM, Osama Mazahir <OSAMAM@microsoft.com> wrote:
> Hi,
>
> Issue #38 [1] tracks:
>         (1) What is the minimum number of concurrent client-initiated streams that a server must be able to support?
>         (2) What is the default value?
>
> We have a race condition where the client can initiate more streams to the server before the server can advertise its stream accept limit to the client.  I suggest making the default the same as the minimum so that we can prevent that race.  And tighten the wording on what is legal.  For example, something like:
>
> A server MUST be able to handle at least 8 concurrent streams initiated by the client. A server MUST NOT advertise a value less than 8. A client MUST generate a session error if it receives a value less than 8 from the server. The default value server limit is 8.
>
> Thanks,
> --Osama.
>
> [1] https://github.com/http2/http2-spec/issues/38
>
>
Received on Saturday, 23 February 2013 20:49:48 GMT

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