[CentOS] leap second

Mon Jul 2 18:45:38 UTC 2012
Les Mikesell <lesmikesell at gmail.com>

On Mon, Jul 2, 2012 at 1:32 PM, Gordon Messmer <yinyang at eburg.com> wrote:
> On 07/02/2012 09:24 AM, Peter Eckel wrote:
>> On the other hand I'm a bit surprised that the problems were
>> comparably few - actually there is a time '01:59:60' for one second,
>> and any plausibility check I've ever seen assumes that minutes and
>> seconds are in the range from 0..59. Wrongly, it seems.
> As far as I've been able to understand it, the problem had nothing to do
> with validity checks or other date handling code.  The problem was
> simply a bug in the API provided by the Linux kernel for notification of
> leap seconds.  The kernel messed up some internal data that led to
> futexes going nuts.  The affected programs weren't handling dates
> poorly, they were just threaded applications.
>> Apparently Google uses an approach that looks much less risky to me -
>> they use a time window over which they 'smear' the leap second by
>> making their time servers lie about the time for a while, making it
>> pass a little bit slower. That way they avoid the unlucky 61st second
>> and still advance the clocks within a reasonable time.
> Google's approach was reliable by chance.  They used a different kernel
> API to adjust the clock, and that one didn't break futexes.

So it wasn't anything special about java?   I did find one one
not-very-busy instance of a Centos 6.x with a java application still
running that did not appear to have a problem.

   Les Mikesell
     lesmikesell at gmail.com