Re: Deadlocking in the transport

Ian Swett <ianswett@google.com> Wed, 10 January 2018 13:46 UTC

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From: Ian Swett <ianswett@google.com>
Date: Wed, 10 Jan 2018 08:46:06 -0500
Message-ID: <CAKcm_gNR30tNVR6hBH7T46+AXsu42e7-Mo6m8ye1sPwkt_WLEQ@mail.gmail.com>
Subject: Re: Deadlocking in the transport
To: Jana Iyengar <jri@google.com>, Martin Thomson <martin.thomson@gmail.com>, QUIC WG <quic@ietf.org>
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I would agree that #4 is the right direction.  GQUIC also does #4, because
it forces all headers to be written before any requests that may depend
upon them are written.

If the application knows there is a dependency, it should be the
application's responsibility to deal with it, not the transport's, which
also points to #4(or maybe #1).

I also think there are use cases for data transfer that is not a stream and
does not consume flow control, but I don't think they solve every problem
and I don't think they should be necessary here.

On Wed, Jan 10, 2018 at 2:05 AM, Dmitri Tikhonov <
dtikhonov@litespeedtech.com>; wrote:

> On Tue, Jan 09, 2018 at 10:49:28PM -0800, Jana Iyengar wrote:
> > Protocols that create inter-stream dependency should be able to express
> > that in priorities down to the transport, which I believe is expected to
> be
> > part of the API. I believe that handles this issue, doesn't it?
>
> When it comes to priorities, the QUIC I-D gives implementations
> some leeway [1].  One cannot guarantee that a conforming
> implementation will not deadlock.
>
>   - Dmitri.
>
> 1. https://tools.ietf.org/html/draft-ietf-quic-transport-08#section-10.6
>
>