Date: Wed, 24 Feb 2010 03:44:41 -0800 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: freebsd-stable@freebsd.org Subject: Re: sleep(3) sometimes too sleepy on FreeBSD 8.0? Message-ID: <20100224114441.GA57760@icarus.home.lan> In-Reply-To: <20100224112139.GT50403@deviant.kiev.zoral.com.ua> References: <20100223013522.GE2303@rwpc12.mby.riverwillow.net.au> <20100224075359.GA61876@server.vk2pj.dyndns.org> <20100224112139.GT50403@deviant.kiev.zoral.com.ua>
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On Wed, Feb 24, 2010 at 01:21:39PM +0200, Kostik Belousov wrote: > On Wed, Feb 24, 2010 at 06:53:59PM +1100, Peter Jeremy wrote: > > Updates following some off-line discussions and debugging with John on > > IRC. I've cc'd gshapiro@ because the problem appears to be sendmail, > > rather than the FreeBSD kernel. > > > > On 2010-Feb-23 12:35:22 +1100, John Marshall <john.marshall@riverwillow.com.au> wrote: > > >Environment: sendmail 8.14.4 on FreeBSD 8.0-RELEASE-p2 > > > > Note that this is stock ISC sendmail, not the sendmail in either the > > base system or the port. > > > > >I posted about this in comp.mail.sendmail and was told... > > > > > >> sleep() should be one of these calls: > > >> > > >> if (njobs == 0 && WorkGrp[wgrp].wg_lowqintvl < MIN_SLEEP_TIME) > > >> sleep(MIN_SLEEP_TIME); > > >> else if (WorkGrp[wgrp].wg_lowqintvl <= 0) > > >> sleep(QueueIntvl > 0 ? QueueIntvl : MIN_SLEEP_TIME); > > >> else > > >> sleep(WorkGrp[wgrp].wg_lowqintvl); > > > > Whilst it's true that the code calls sleep(), it's not calling > > sleep(3) in the FreeBSD libc. Instead it's calling a sleep() defined > > in libsm/clock.c - which is a horrible maze of #ifdefs. > > > > John has pre-processed that code and the result it at: > > http://www.riverwillow.net.au/~john/sm/clock.preprocessed > > > > At a quick look, the code is broken: sm_seteventm() generates a > > one-off timer using setitimer(2), which will send SIGALRM when it > > expires. sm_releasesignal() then unblocks SIGALRM. In theory, the > > SIGALRM could be delivered anywhere after the (!SmSleepDone) test and > > before pause() is called - in which case, the signal is lost and > > pause() will sleep forever. > > > > On 2010-Feb-24 08:13:06 +1100, John Marshall <john.marshall@riverwillow.com.au> wrote: > > >My ktrace file was created with 'ktrace -g 48501'. I have the result of > > >'kdump -R -p 48504' available at: > > > > > > <http://www.riverwillow.net.au/~john/8_0/rwsrv04_201002240725.kdump.gz>; > I get 'kdump: data too short' on RELENG_8/i386. Is the OP's machine amd64? -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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