From owner-svn-src-head@FreeBSD.ORG Mon Oct 15 22:21:32 2012 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 30215CC3; Mon, 15 Oct 2012 22:21:32 +0000 (UTC) (envelope-from delphij@delphij.net) Received: from anubis.delphij.net (anubis.delphij.net [IPv6:2001:470:1:117::25]) by mx1.freebsd.org (Postfix) with ESMTP id 0986F8FC0A; Mon, 15 Oct 2012 22:21:32 +0000 (UTC) Received: from epsilon.delphij.net (drawbridge.ixsystems.com [206.40.55.65]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by anubis.delphij.net (Postfix) with ESMTPSA id BD5F51DB1E; Mon, 15 Oct 2012 15:21:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=delphij.net; s=anubis; t=1350339691; bh=BCVaqHDNRiga+vozp8KmS/IJWvKwI7JfaQ8K5ms/gXc=; h=Date:From:Reply-To:To:CC:Subject:References:In-Reply-To; b=f9IQsKWpgHuZGgw21lDEZNKbM0iMydK/8zBnXYCu4FZT7b5kIVj16klIrqAfJYm67 uyxidSPU2Uuxg9mHfkYAU4XP1WOldazjK9y2Ktrk5Z2F6RazZ+JmINLT6awNjpZA1V pAEH04C6UU/k287lHmG7p5ps5TAkSxph4XSwMy2E= Message-ID: <507C8C6B.80707@delphij.net> Date: Mon, 15 Oct 2012 15:21:31 -0700 From: Xin Li Organization: The FreeBSD Project MIME-Version: 1.0 To: Garrett Cooper Subject: Re: svn commit: r241576 - in head/usr.sbin/cron: cron crontab lib References: <201210150821.q9F8Lobc047576@svn.freebsd.org> <20121015202615.GJ1383@garage.freebsd.pl> <1350333885.1123.153.camel@revolution.hippie.lan> In-Reply-To: X-Enigmail-Version: 1.4.5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Ian Lepore , src-committers@freebsd.org, Pawel Jakub Dawidek , Maxim Sobolev , svn-src-all@freebsd.org, svn-src-head@freebsd.org X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: d@delphij.net List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 15 Oct 2012 22:21:32 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 10/15/12 13:52, Garrett Cooper wrote: > On Mon, Oct 15, 2012 at 1:44 PM, Ian Lepore > wrote: >> On Mon, 2012-10-15 at 22:26 +0200, Pawel Jakub Dawidek wrote: >>> On Mon, Oct 15, 2012 at 08:21:50AM +0000, Maxim Sobolev wrote: >>>> Author: sobomax Date: Mon Oct 15 08:21:49 2012 New Revision: >>>> 241576 URL: http://svn.freebsd.org/changeset/base/241576 >>>> >>>> Log: Add per-second scheduling into the cron(8). Right now >>>> it's only available via the new @every_second shortcut. >>>> ENOTIME to implement crontab(5) format extensions to allow >>>> more flexible scheduling. >>>> >>>> In order to address some concerns expressed by Terry Lambert >>>> while discussing the topic few years ago, about per-second >>>> cron possibly causing some bad effects on /etc/crontab by >>>> stat()ing it every second instead of every minute now (i.e. >>>> atime update), only check that database needs to be reloaded >>>> on every 60-th loop run. This should be close enough to the >>>> current behaviour. >>>> >>>> Add "@every_minute" shortcut while I am here. >>> >>> Do I read the code correctly and the cron deamon will wake up >>> every second now even if @every_second is not used at all? >> >> It appears to, which I don't think is a bad thing at all. But >> the way it waits is to wake up, do some work, and go back to >> sleep for an integer 1 second. That will occasionally lead to a >> second in which no wakeup happens, as the "do some work" part >> always takes some fraction of a second. > > This is silly. It should be waking up at the lowest common > denominator of time quanta, not every second; this could be > determined via the crontab its managing. This will break crontab change detection -- instead of pickup the change in a minute, now you end up with the smallest common divisor. BTW it seems that I need to clean dust on my forever WIP cron update sooner :-/ Cheers, - -- Xin LI https://www.delphij.net/ FreeBSD - The Power to Serve! Live free or die -----BEGIN PGP SIGNATURE----- iQEcBAEBCAAGBQJQfIxrAAoJEG80Jeu8UPuz8AEH/RHsUiCrbjws2GwyNcIn2Qz5 JEkmK4SAvMigIok2JZNyuKtP/6j9wmhk6EtuDLV9s196hdarfBPl/JJcv7x+JM/W OTOtJuh8i59bTNSSUPVUlgEpXXh8I77CfVO3RfadcchCMzkhUuonHGpgqVflYS4n LbjJEbZMrGq7JSat3kjUX6bU+jOb2cA1Ieoe9ykp3vsFZWHFeAimMzPcH/knO/wi M9YgzO4mfuATYUDDcj6Istvm2O3mwsftPwTPCe2RUov5fvWG05InygwqglaYtvx9 e6tKYqbwbd+kVr9ZOLVc9Izk51b3pATDuItYDSXUyI2DW8ymsgvvdk2vOkZfDnQ= =q1rQ -----END PGP SIGNATURE-----