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Old 07-02-2012, 08:02 PM
Gordon Messmer
 
Default leap second

On 07/02/2012 12:54 PM, Les Mikesell wrote:
> Sooo... Are the 6.x boxes that did not exhibit a problem yet still
> likely to have it if you start a threaded program or did it have to
> happen in the 1 second window?

As far as I know, it could still pop up. The futex handling in the
kernel will be screwed up until the system reboots, or until the time is
set using an API that wasn't affected by the bug. That's why one of the
recommended fixes is just to:

date -s "`date`"


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Old 07-02-2012, 08:06 PM
 
Default leap second

Gordon Messmer wrote:
> On 07/02/2012 12:54 PM, Les Mikesell wrote:
>> Sooo... Are the 6.x boxes that did not exhibit a problem yet still
>> likely to have it if you start a threaded program or did it have to
>> happen in the 1 second window?
>
> As far as I know, it could still pop up. The futex handling in the
> kernel will be screwed up until the system reboots, or until the time is
> set using an API that wasn't affected by the bug. That's why one of the
> recommended fixes is just to:
>
> date -s "`date`"

Dumb question, but I haven't followed this thread that closely - been busy
at work - but why not
$ service ntp stop
$ ntpdate
$ service ntp start
?
mark

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Old 07-02-2012, 08:38 PM
Gordon Messmer
 
Default leap second

On 07/02/2012 01:06 PM, m.roth@5-cent.us wrote:
> Dumb question, but I haven't followed this thread that closely - been busy
> at work - but why not
> $ service ntp stop
> $ ntpdate
> $ service ntp start

Today that might work, but would be slower than using "date". On
Saturday, I think that would have triggered the bug.

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Old 07-02-2012, 10:52 PM
Warren Young
 
Default leap second

On 7/2/2012 10:24 AM, Peter Eckel wrote:
>
> ... and leap seconds are not even scarce.

An event on an unpredictable schedule averaging 1.7 years since 1972
doesn't count as "scarce"?

That's the answer to Les's outrage, too, by the way. Might as well
expect the JRE to have code to deal with cosmic ray damage that gets by
ECC, too.
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Old 07-02-2012, 10:58 PM
Warren Young
 
Default leap second

On 7/2/2012 2:06 PM, m.roth@5-cent.us wrote:
>
> Dumb question, but I haven't followed this thread that closely - been busy
> at work - but why not
> $ service ntp stop
> $ ntpdate
> $ service ntp start

Because that results in a call to adjtimex(2), which is also the syscall
used by ntpd, which in turn is affected by the kernel bug.

Calling date(1) instead uses the clock_settime(2) syscall, which isn't
affected.

One isn't implemented in terms of the other, for reasons that should be
obvious from the manpages.
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Old 07-02-2012, 11:15 PM
Les Mikesell
 
Default leap second

On Mon, Jul 2, 2012 at 5:52 PM, Warren Young <warren@etr-usa.com> wrote:
> On 7/2/2012 10:24 AM, Peter Eckel wrote:
>>
>> ... and leap seconds are not even scarce.
>
> An event on an unpredictable schedule averaging 1.7 years since 1972
> doesn't count as "scarce"?

"Unpredictible" means you don't know something is coming in time to
test for what to expect from its effect. I don't see how that applies
here.

> That's the answer to Les's outrage, too, by the way. Might as well
> expect the JRE to have code to deal with cosmic ray damage that gets by
> ECC, too.

Well, if there were a well known, long-standing API for that, and the
time it was going to happen announced months ahead yes, I would expect
it to be tested too. But, per the earlier discussion it is a kernel
bug, not the JRE. I'd sort of expect java builds to have unit tests
for their APIs.

--
Les Mikesell
lesmikesell@gmail.com
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Old 07-03-2012, 09:22 AM
 
Default leap second

-----Original Message-----
From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Stephen Harris
Sent: Monday, July 02, 2012 6:24 PM
To: CentOS mailing list
Subject: Re: [CentOS] leap second

On Mon, Jul 02, 2012 at 11:09:41AM -0500, Les Mikesell wrote:
> I'm sort of curious about how a bug of this magnitude slips through
> the QA process (into java and RHEL, not CentOS). With all the furor
> about y2k, did no one even bother to simulate a leap second ahead of
> the real occurrence?

The kernel bug is a race condition; simulations may not have detected
it.
-----Original Message-----

Very well, but this isn't the first leap second-insertion (2005, 2009), and certainly not the last.
I never heard of such consequences before.

Hans

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Old 07-06-2012, 01:41 PM
Nicolas Ross
 
Default leap second

> You could have just done:
> service ntpd stop; date -s "`date`"; service ntpd start
> Fixed here without even stopping any jvm.
Would have loved to know that then ;-)

We have 2 8-node clusters that runs many java applications, and many
java applications on seperate servers. I went nuts when all java running
servers cam to 100% cpu all at once !

The guy I spoke to at RedHat GSS at about 00:45 UTC baiscly told me to
reboot the server, wich ended up rebooting our 2 clusters... Bad... But
since computers all over the world crashed, our clients did understood
that the problem was far lower than they beleived it...
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