From mboxrd@z Thu Jan  1 00:00:00 1970
MIME-Version: 1.0
In-Reply-To: <AANLkTikX=TOj5_k8mG88O0Lfnb-uGDK6BzkuMZqGACzQ@mail.gmail.com>
References: <AANLkTinhzWx+-t95OsqRZ=_5WZFjcpG33H-imyq4a6-V@mail.gmail.com>
	<35dbd2d8996bf96d65c969836bd2e172@terzarima.net>
	<AANLkTikX=TOj5_k8mG88O0Lfnb-uGDK6BzkuMZqGACzQ@mail.gmail.com>
Date: Fri, 29 Oct 2010 16:37:22 +1100
Message-ID: <AANLkTimjX8bCwrCmKSGzc+SkBvCzxTK3XJg2-J_-qORL@mail.gmail.com>
From: Bruce Ellis <bruce.ellis@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Subject: Re: [9fans] A little more ado about async Tclunk
Topicbox-Message-UUID: 70f19632-ead6-11e9-9d60-3106f5b1d025

No! Open on an exclusive file has the same races. No problems on
Froggie .. no servers with clunk semantics. The first I encountered
was Bosch's video streamer. Nemo obviously has concerns.

Catch a run.

brucee

On Fri, Oct 29, 2010 at 10:51 AM, Gorka Guardiola <paurea@gmail.com> wrote:
> On Thu, Oct 28, 2010 at 10:18 PM, Charles Forsyth <forsyth@terzarima.net>=
 wrote:
>>
>> the race is that there's nothing to say that the clunk completes before =
the
>> process continues on to do something more, including some action that de=
pends on the clunk completing,
>> such as simply repeating the open. that open can fail if the mode or the=
 name
>> imposes particular constraints; constraints that depend on the order of =
events as
>> expressed by the process.
>
> What you are saying is that the problem could be something like:
>
> -> Tclunk
> (do not wait for response)
> -> Topen (the file is exclusive)
>
> Then somehow in the server, Tclunk and Topen are reordered because
> they are managed
> by different threads and Topen gets an error because the file is already =
opened.
>
> This is a problem, I agree.
>
>> On Oct 28, 2010, at 10:32 PM, Venkatesh Srinivas <me@acm.jhu.edu> wrote:
>> On a decent server, since clunk cannot fail and won't launch the missile=
s, you can't really do anything that would depend on the result anyway.
>
> Tclunk may be a good time to commit to disk or do other unmissile like th=
ing.
> You can switch to another cache after waiting for the Rclunk, for example=
.
>
> Decent or not indecent I am more and more conviced after this thread that
> Tclunk should be synchronous. Even in decent files Tclunk can =A0have
> some side effects.
>
>