Feeds

Google reveals 'leap smear' NTP technique

Copes with problems of living on spinning space boulder

Intelligent flash storage arrays

Google has to lie to computers in order not to upset them with the vagaries of earthly time.

The text-ads colossus has just written a blog post on how it adjusts its computer systems to deal with leap seconds – by lying to them a bit with a technique it calls "leap smear", where the search giant adds a few milliseconds bit by bit in the time period up to the leap second. It involves blurring time a bit – in a way that computers can deal with. Smart eh?

The Chocolate Factory talks us through the tech in a post on The Google Blog:

The solution we came up with came to be known as the 'leap smear'. We modified our internal Network Time Protocol [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.

Leap days come once every four years, but leap seconds get added on as and when we need them – there have been 24 since 1972 – and make up for the inconsistencies in the length of the earthly year. Inconsistencies that come from being an earthquake-troubled irregularly-shaped spinning piece of rock orbiting its star 150 million kilometers (93 million miles) away.

Since 1972, timekeepers have added (or subtracted) an extra second at the end of a particular day once every few years, but as computer systems have become more complex, having a rogue extra second can cause a lot of trouble.

We can lie to the computer clock, but we can't lie to ourselves forever though. We're still little collections of carbon molecules spinning around on some rock in the abyss. What can we do about that, Google? Eh? Thought so. ®

Beginner's guide to SSL certificates

More from The Register

next story
Apple CEO Tim Cook: My well-known gayness is 'a gift from GOD'
'I have benefited from the sacrifice of others'
MEN: For pity's sake SLEEP with LOTS of WOMEN - and avoid Prostate Cancer
And, um, don't sleep with other men. If that's what worries you
Jim Beam me up, Scotty! WHISKY from SPAAACE returns to Earth
They're insured for $1m, before you thirsty folks make plans
Now: The REAL APPLE NEWS you need to know
OMG! Gravity's totes amazeballs. Calm down, George Clooney, not your film
Boffins who stare at goats: I do believe they’re SHRINKING
Alpine chamois being squashed by global warming
Let's make an app that POSTS your POO to APPLE HQ
Plus: It's OPEN WARFARE in the Linux greybeard world
Adorkable overshare of words like photobomb in this year's dictionaries
And hipsters are finally defined as self-loathing. Sort of
Not a loyal follower of @BritishMonarchy? You missed The QUEEN*'s first Tweet
Her Maj opens 'Information Age' at the Science Museum
prev story

Whitepapers

Choosing cloud Backup services
Demystify how you can address your data protection needs in your small- to medium-sized business and select the best online backup service to meet your needs.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
New hybrid storage solutions
Tackling data challenges through emerging hybrid storage solutions that enable optimum database performance whilst managing costs and increasingly large data stores.
Protecting users from Firesheep and other Sidejacking attacks with SSL
Discussing the vulnerabilities inherent in Wi-Fi networks, and how using TLS/SSL for your entire site will assure security.