NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Time up for the leap second?
From: Richard B. Langley
Date: 2012 Jan 17, 22:59 -0400
From: Richard B. Langley
Date: 2012 Jan 17, 22:59 -0400
A similar approach is used to sync up the clock in the tower at Westminster ("Big Ben" -- although that is really the name of the largest bell in the tower) on the evening of the leap second by gradually taking off some of the old pennies in a tray near the top of the clock's pendulum. -- Richard Langley Quoting Frank Reed: > You may reasonably imagine that this is easy and computers have it > all programmed in, but it's an illusion. Computer code for > networking has developed in an organic fashion. At the end of 2008, > the folks who manage Google's servers chose to skip the leap second > in the proper sense, and instead they inserted 1000 one-millisecond > delays (equivalent) during the course of the day on December 31, > 2008. As their official blog described it: > "The solution we came up with came to be known as the 'leap smear.' > We modified our internal NTP servers to gradually add a couple of > milliseconds to every update, varying over a time window before the > moment when the leap second actually happens. This meant that when > it became time to add an extra second at midnight, our clocks had > already taken this into account, by skewing the time over the course > of the day. All of our servers were then able to continue as normal > with the new year, blissfully unaware that a leap second had just > occurred. We plan to use this 'leap smear' technique again in the > future, when new leap seconds are announced by the IERS." > > -FER > > ---------------------------------------------------------------- > NavList message boards and member settings: www.fer3.com/NavList > Members may optionally receive posts by email. > To cancel email delivery, send a message to NoMail[at]fer3.com > ---------------------------------------------------------------- ----------------------------------------------------------------------------- | Richard B. Langley E-mail: lang@unb.ca | | Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ | | Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 | | University of New Brunswick Fax: +1 506 453-4943 | | Fredericton, N.B., Canada E3B 5A3 | | Fredericton? Where's that? See: http://www.fredericton.ca/ | -----------------------------------------------------------------------------