From mboxrd@z Thu Jan  1 00:00:00 1970
X-Msuck: nntp://news.gmane.io/gmane.comp.sysutils.supervision.general/1970
Path: news.gmane.org!not-for-mail
From: Charlie Brady <charlieb-supervision@budge.apana.org.au>
Newsgroups: gmane.comp.sysutils.supervision.general
Subject: Re: svwaitup races with sv
Date: Fri, 24 Jul 2009 16:31:00 -0400 (EDT)
Message-ID: <Pine.LNX.4.64.0907241627160.18966@e-smith.charlieb.ott.istop.com>
References: <8F9355C5-C168-4AD7-8B6C-502416E7EECC@zoy.org>
 <Pine.LNX.4.64.0907130942001.359@e-smith.charlieb.ott.istop.com>
 <94175859-2733-4ACF-85E9-DD5FF627F23B@zoy.org> <17A739BC-94BA-4611-A523-6978934F0D61@zoy.org>
 <loom.20090717T090207-38@post.gmane.org> <4A633321.1060207@agilent.com>
 <4A635477.6030503@agilent.com>
NNTP-Posting-Host: lo.gmane.org
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
X-Trace: ger.gmane.org 1248467491 3600 80.91.229.12 (24 Jul 2009 20:31:31 GMT)
X-Complaints-To: usenet@ger.gmane.org
NNTP-Posting-Date: Fri, 24 Jul 2009 20:31:31 +0000 (UTC)
Cc: supervision@list.skarnet.org
To: Earl Chew <earl_chew@agilent.com>
Original-X-From: supervision-return-2205-gcsg-supervision=m.gmane.org@list.skarnet.org Fri Jul 24 22:31:24 2009
Return-path: <supervision-return-2205-gcsg-supervision=m.gmane.org@list.skarnet.org>
Envelope-to: gcsg-supervision@gmane.org
Original-Received: from antah.skarnet.org ([212.85.147.14])
	by lo.gmane.org with smtp (Exim 4.50)
	id 1MURQ7-0000WD-Od
	for gcsg-supervision@gmane.org; Fri, 24 Jul 2009 22:31:11 +0200
Original-Received: (qmail 31636 invoked by uid 76); 24 Jul 2009 20:32:28 -0000
Mailing-List: contact supervision-help@list.skarnet.org; run by ezmlm
List-Post: <mailto:supervision@list.skarnet.org>
List-Help: <mailto:supervision-help@list.skarnet.org>
List-Unsubscribe: <mailto:supervision-unsubscribe@list.skarnet.org>
List-Subscribe: <mailto:supervision-subscribe@list.skarnet.org>
List-Archive: <http://www.skarnet.org/lists/>
Original-Received: (qmail 31626 invoked from network); 24 Jul 2009 20:32:28 -0000
X-X-Sender: charlieb@e-smith.charlieb.ott.istop.com
In-Reply-To: <4A635477.6030503@agilent.com>
Xref: news.gmane.org gmane.comp.sysutils.supervision.general:1970
Archived-At: <http://permalink.gmane.org/gmane.comp.sysutils.supervision.general/1970>


On Sun, 19 Jul 2009, Earl Chew wrote:

> The script below generates the following output:
>
>>  down: ./svc: 0s
>>  svwaitup: warning: ./svc: is down.
>>  .... WaitUp 1
>>  Try again
>>  run: ./svc: (pid 8496) 2s, normally down, want down
>
> It illustrates a race between runsv/sv and svwaitup.
...
> It would be better if sv(8) itself could synchronise.

I think that would be possible by making the fifo unbuffered, and having 
sv inject a nop command during 'sv status' (so sv would be blocked until 
runsv had processed previous commands). But that would change the timing 
of lots of current programs which call 'sv'.