Re: Deadlocking in the transport

Dmitri Tikhonov <dtikhonov@litespeedtech.com> Wed, 10 January 2018 20:24 UTC

Return-Path: <dtikhonov@litespeedtech.com>
X-Original-To: quic@ietfa.amsl.com
Delivered-To: quic@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id BCA8E12711B for <quic@ietfa.amsl.com>; Wed, 10 Jan 2018 12:24:02 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.601
X-Spam-Level:
X-Spam-Status: No, score=-2.601 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=litespeedtech-com.20150623.gappssmtp.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id jAYHAilYLFH0 for <quic@ietfa.amsl.com>; Wed, 10 Jan 2018 12:24:01 -0800 (PST)
Received: from mail-qk0-x22c.google.com (mail-qk0-x22c.google.com [IPv6:2607:f8b0:400d:c09::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 04A11126DED for <quic@ietf.org>; Wed, 10 Jan 2018 12:24:00 -0800 (PST)
Received: by mail-qk0-x22c.google.com with SMTP id j137so645191qke.10 for <quic@ietf.org>; Wed, 10 Jan 2018 12:24:00 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=litespeedtech-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to:user-agent; bh=E3+esAT+xlCJlOl8rLTfQ1hW79GPnyDTSvWEdztQu3c=; b=XU7ZICrCAlRBtcc3HP810RijNoT5fnvQjqa0dWP2aK6hnsjExe7lNR74qlxwmOFYH9 YVzz1h3VzJ0welandGc+Tb7ZHLD+eYgceJaAC43ruvdzs0i1bB535usVi/bGjEhk/Rnj p6E3RDmqiEa3wDKmT5ubrEhnbjjh/s+xWufa2KHrgFk8pEjmox/1mpkRRFWpihzlZBqc +rnknl/nymhEdD2MV6SpYxzUJ7ZeXkYetn6c3McKudQXwwVKPzPvtIRiTnmrYdVtF5M0 iEaqpmMj0Xw15myEUFDeD8qfoL7UHWwYeN1k14A1ai99F0D+XwIIX4dGtHoFziEOmfTe VTeA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to:user-agent; bh=E3+esAT+xlCJlOl8rLTfQ1hW79GPnyDTSvWEdztQu3c=; b=MLq6w170ap9RB+3beXFOlWHNvuWRJS6VUJ7NcgvX6YRcAUJ2ZG26GwgEMl9IqOjsCi dZoIsklMPBF0L1r+MWpg6uHI6hXZPCms4LlEImLvukMuIs5rGc3cDj4PeObPQRwQ+HFb Df9JmcyL24kcu51iLGSNFBCwwqDqc2LuD71BXHzzWLYsa9G8mlkC4zDz/x83RPf3uwq3 ljSxlBBsex6vUHi0wzfBeZ0ho9GfDd2V/qnIhymwz4U1zoYjTBwcjrP/QzJ+ZIGb5mIx UHsjj9exgJBEASBFZ8VUMdZpfj8PzNRB6qY3bO9VlIBiYGlpHI3+KxgidigZxkl0ZTt9 E4Ig==
X-Gm-Message-State: AKwxytcCbPcYVzPF4cRQxuu+CpE4P6cweTVRnWYoOhoAkbeTMi9tS7pb bK3XHyhlezfhvdezDPDq4liHGQ==
X-Google-Smtp-Source: ACJfBotdemj+PwUEXDZ1n5CaIsjIDHa9CerKuU5glim0rRZKzv/g5n9s6kKtw3IhTgEtyUCuc0ARTg==
X-Received: by 10.55.215.139 with SMTP id t11mr24584609qkt.355.1515615839857; Wed, 10 Jan 2018 12:23:59 -0800 (PST)
Received: from ubuntu-dmitri (ool-2f1636b6.static.optonline.net. [47.22.54.182]) by smtp.gmail.com with ESMTPSA id s126sm3977886qkh.59.2018.01.10.12.23.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 10 Jan 2018 12:23:59 -0800 (PST)
Date: Wed, 10 Jan 2018 15:23:57 -0500
From: Dmitri Tikhonov <dtikhonov@litespeedtech.com>
To: Jana Iyengar <jri@google.com>
Cc: Charles 'Buck' Krasic <ckrasic@google.com>, QUIC WG <quic@ietf.org>, Martin Thomson <martin.thomson@gmail.com>
Subject: Re: Deadlocking in the transport
Message-ID: <20180110202357.GC30573@ubuntu-dmitri>
Mail-Followup-To: Jana Iyengar <jri@google.com>, Charles 'Buck' Krasic <ckrasic@google.com>, QUIC WG <quic@ietf.org>, Martin Thomson <martin.thomson@gmail.com>
References: <CABkgnnUSMYRvYNUwzuJk4TQ28qb-sEHmgXhxpjKOBON43_rWCg@mail.gmail.com> <CAGD1bZYV7iHg_YarUMqUSnpbAB2q8dwEWO=dHE2wbw8Oea_zfA@mail.gmail.com> <CAD-iZUY-Y-MO_T74JmP6B9XVj=91eVovfcWnE=9s9kd0Ji+CnA@mail.gmail.com> <CAGD1bZa7ugOTT11qOKfCm4NFdi+t-pdrXnscWHgg0bO5tgUqmg@mail.gmail.com> <20180110194716.GA30573@ubuntu-dmitri> <CAGD1bZYiDOakLYNppMBr=99JreX3Xr2zkS7O2DRNfvr_o0NUbg@mail.gmail.com> <20180110200646.GB30573@ubuntu-dmitri> <CAGD1bZa-ZOw5J6oSWBYdk3uYHOpGvak+vwGp0XsZB44zbLvRrw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAGD1bZa-ZOw5J6oSWBYdk3uYHOpGvak+vwGp0XsZB44zbLvRrw@mail.gmail.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic/wNKCkvx30WKvnx4Ae3c8REdzXGs>
X-BeenThere: quic@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Main mailing list of the IETF QUIC working group <quic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic>, <mailto:quic-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic/>
List-Post: <mailto:quic@ietf.org>
List-Help: <mailto:quic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic>, <mailto:quic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 10 Jan 2018 20:24:03 -0000

On Wed, Jan 10, 2018 at 12:14:13PM -0800, Jana Iyengar wrote:
> SHOULD is pretty strong. It's not a guarantee, but then a transport
> implementation that doesn't do it is expected to know what it's doing.

If an application protocol is based on an assumption that the transport's
SHOULD is really a MUST, then you end up with an application that works
with some transport implementations, but not other -- conforming! --
implementations.

> We could include language in this section about priorities being important
> to avoid deadlocks when an application has dependencies across streams.

What would this advice be?  "Consume *all data* from higher priority
streams before consuming data from lower priority streams?"

  - Dmitri.