Re: Setting to disable HTTP/2 Priorities

Lucas Pardue <> Fri, 26 July 2019 03:51 UTC

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From: Lucas Pardue <>
Date: Thu, 25 Jul 2019 23:48:40 -0400
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To: Willy Tarreau <>
Cc: Brad Lassey <>, HTTP Working Group <>
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Subject: Re: Setting to disable HTTP/2 Priorities
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Hi Willy!

On Thu, 25 Jul 2019, 23:23 Willy Tarreau, <> wrote:

> Hi Brad,
> On Thu, Jul 25, 2019 at 02:49:52PM -0400, Brad Lassey wrote:
> > Hi all,
> > Lucas and I put together a draft to capture at least one of the ways
> > forward that were identified at the priorities side meeting yesterday
> > morning. Please have a look.
> >
> >
> >
> While I think that's a very wise approach, I think it would have more
> success if it doesn't change the default behaviour. I mean, some
> developers on both sides have gone through great length implementing
> priorities and expecting now that they should suddenly have to add
> extra code to continue to use them might be difficult to accept.
> Conversely, all those who didn't implement them would have a great
> incentive to add a few lines of code to signal their lack of support
> and immediately expect a better experience. Thus I think priorities
> should remain enabled unless signaled as disabled by this new setting.

The aim is to maintain todays default behavior of endpoints supporting H2.
This is achieved by defining the initial value of the setting as 1;
endpoints "opt out" by sending 0.

Do you think we have mis-specced this compared to our aim?

And for having been late to implement them into haproxy (still not
> present), I'd definitely adopt this proposal as a temporary measure
> if it helps improve user experience!

That's an interesting data point, thanks for sharing.