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Darien Caldwell · 06-29-2012, 04:04 PM

An Extra second will be added at Midnight Saturday. Be sure to adjust your Atomic Clocks!

Don't get left in the past...

The Science Behind Saturday's Leap Second - Yahoo! News

On a more serious note, it seems there's some actual controversy around this:

http://www.madore.org/~david/compute...p-seconds.html

I wonder what LL will do...

Imnotgoing Sideways · 06-29-2012, 04:06 PM

GPS clocks don't recognize the silly little leap second. =^-^=

Darien Caldwell · 06-29-2012, 04:19 PM

I was reading some Google forums about this and it seems their Site Reliability Engineering Group (SREG) decided lying about the time was best:

Quote:

doing this, we applied a patch to the NTP server software on our internal Stratum 2 NTP servers to *not set* LI, and tell a small “lie” about the time, modulating this “lie” over a time window *w* before midnight

Quote:

...one of our coolest workarounds, that took a lot of experimentation and verification, but paid off by ultimately saving us massive amounts of time and energy in inspecting and refactoring code.

So i guess they will stretch the leap second across one or more real-world seconds as reported by their NTP server. interesting approach.

**Soen Eber** · 06-29-2012, 04:31 PM

The moon

is such

a drag.

**Void** · 06-29-2012, 07:13 PM

Quote:

Originally Posted by Darien Caldwell

I was reading some Google forums about this and it seems their Site Reliability Engineering Group (SREG) decided lying about the time was best:

So i guess they will stretch the leap second across one or more real-world seconds as reported by their NTP server. interesting approach.

this seems like a bit of fluff to me... are their cross server applications using subsecond time check precision? and if there are, how often are they polling NTP to maintain it? seems more than just a bit silly.

**yure4u Sosa** · 06-29-2012, 08:56 PM

wot???? i find this thread more fun Be Sure to Adjust your Cocks Saturday!

Darien Caldwell · 06-29-2012, 10:43 PM

Quote:

Originally Posted by Void

this seems like a bit of fluff to me... are their cross server applications using subsecond time check precision? and if there are, how often are they polling NTP to maintain it? seems more than just a bit silly.

here's the full article:

Official Google Blog: Time, technology and leaping seconds

When you consider the volume of traffic Google handles, having a second repeat twice could potentially cause issues. I think they just want to be more safe than sorry from what I read.

**Void** · 06-30-2012, 04:21 AM

just seems very wrong to rely on that much precision against the real world clock... NTP is supposed to be more robust than that and it's ZOMG SHIT IS SERIOUSLY BORKED! threshold something like 15 minutes....

LoriClaremont · 06-30-2012, 06:31 AM

But but but, adding a leap second doesn't require repeating a second....

When the leap second is added the minute in question counts from 0 to 60 instead of 0 to 59 (at least, that's how I recall the NTP standard specifying it). That said, I can see where a lot of software systems are going to go SPUNG when they query the time and get 11:59:60 for the time...

Smearing the leap second over a few seconds seems like a clever approach though it would be good to have that as part of the official standard I think, that way any systems that do rely on NTP to maintain sub-second synchronization can depend on it even during a leap second.

Darien Caldwell · 07-01-2012, 03:50 PM

Seems many experienced Linux Crashes due to the Leap Second. Never underestimate the ability for a system to fail!

debian - Anyone else experiencing high rates of Linux server crashes during a leap second day? - Server Fault

**Void** · 07-01-2012, 06:33 PM

:: laughs ::

if you read down there's a perfect description of what caused the problem.... the source of the problem was.... trying to solve the problem! =D

the local machine, rather than try to update it's clock directly from the NTP tries to actually handle the leap second on it's own, when it's been flagged. to do so requires extra code and handling.... and that code had a potential race condition that can cause a freeze-crash in the OS.

the thing is... that extra code for handling leap seconds is part of the NTP spec.... you are supposed to do that.... and yet, if the extra code wasn't there on the local side, you'd simply synch up as normal when NTP had a time that's 1 second off. so it turned out that an overthought original solution led to a worse problem than it was supposed to solve.

ETA:
and that dependency I was wondering about... turns out to be NTP itself =D

Govi · 07-01-2012, 06:37 PM

Quote:

Originally Posted by yure4u Sosa

wot???? i find this thread more fun Be Sure to Adjust your Cocks Saturday!

Did you adjust yours?

Jopsy Pendragon · 07-01-2012, 09:48 PM

I think the seconds on my clock are accurate... but it's still off a +/- a few week days. Sigh. =)

What is today anyway?

Govi · 07-01-2012, 10:10 PM

Quote:

Originally Posted by Jopsy Pendragon

I think the seconds on my clock are accurate... but it's still off a +/- a few week days. Sigh. =)

What is today anyway?

It's later than you think.

Jopsy Pendragon · 07-01-2012, 10:20 PM

Quote:

Originally Posted by Govi

It's later than you think.

I have that thought every June when my birthday rolls around.

Govi · 07-02-2012, 12:33 AM

One second sooner than you thought it would, too. That's gonna be a big surprise, come next June.

06-29-2012, 04:04 PM	#1 (permalink)
Darien Caldwell Senior Member Mayan Time Lord Join Date: Apr 2008 Location: Cali Posts: 1,992 My Mood: SL Join Date: 10/12/2006 Business: [H]arsh Styles Client: Always changing, and too lazy to edit.	Be Sure to Adjust your Clocks Saturday! An Extra second will be added at Midnight Saturday. Be sure to adjust your Atomic Clocks! Don't get left in the past... The Science Behind Saturday's Leap Second - Yahoo! News On a more serious note, it seems there's some actual controversy around this: http://www.madore.org/~david/compute...p-seconds.html I wonder what LL will do... __________________ [H]arsh Styles

06-29-2012, 04:06 PM	#2 (permalink)
Imnotgoing Sideways - Join Date: Jun 2008 Location: Darkly Cute :: Ferguson Posts: 6,916 My Mood: SL Join Date: November, 2007 Business: Darkly Cute Client: NOT the same one I used yesterday... (<.<)	GPS clocks don't recognize the silly little leap second. =^-^= __________________ Link

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06-29-2012, 04:31 PM	#4 (permalink)
Soen Eber blink *SLU Supporter* don't need status Join Date: Oct 2009 Location: Minneapolis, Minnesota, USA Posts: 3,366 My Mood:	The moon is such a drag.

06-29-2012, 08:56 PM	#6 (permalink)
yure4u Sosa ┌( ಠ_ಠ)┘ *SLU Supporter* animating Join Date: Apr 2009 Location: ekus house Posts: 855 My Mood: Amazon Quest Champion!Tournaments Won: 1 Business: Kinki Animations	wot???? i find this thread more fun Be Sure to Adjust your Cocks Saturday!

06-30-2012, 04:21 AM	#8 (permalink)
Void That Bitch *SLU Supporter* Innocent as far as you know Join Date: Nov 2011 Location: Online Posts: 6,188 My Mood: SL Join Date: late 04... that account is deleted now	just seems very wrong to rely on that much precision against the real world clock... NTP is supposed to be more robust than that and it's ZOMG SHIT IS SERIOUSLY BORKED! threshold something like 15 minutes....

06-30-2012, 06:31 AM	#9 (permalink)
LoriClaremont Senior Member This space for rent Join Date: Jan 2011 Location: San Francisco area Posts: 193 My Mood: SL Join Date: 5/30/2009 Client: Firestorm	But but but, adding a leap second doesn't require repeating a second.... When the leap second is added the minute in question counts from 0 to 60 instead of 0 to 59 (at least, that's how I recall the NTP standard specifying it). That said, I can see where a lot of software systems are going to go SPUNG when they query the time and get 11:59:60 for the time... Smearing the leap second over a few seconds seems like a clever approach though it would be good to have that as part of the official standard I think, that way any systems that do rely on NTP to maintain sub-second synchronization can depend on it even during a leap second.

07-01-2012, 03:50 PM	#10 (permalink)
Darien Caldwell Senior Member Mayan Time Lord Join Date: Apr 2008 Location: Cali Posts: 1,992 My Mood: SL Join Date: 10/12/2006 Business: [H]arsh Styles Client: Always changing, and too lazy to edit.	Seems many experienced Linux Crashes due to the Leap Second. Never underestimate the ability for a system to fail! debian - Anyone else experiencing high rates of Linux server crashes during a leap second day? - Server Fault

07-01-2012, 06:33 PM	#11 (permalink)
Void That Bitch *SLU Supporter* Innocent as far as you know Join Date: Nov 2011 Location: Online Posts: 6,188 My Mood: SL Join Date: late 04... that account is deleted now	:: laughs :: if you read down there's a perfect description of what caused the problem.... the source of the problem was.... trying to solve the problem! =D the local machine, rather than try to update it's clock directly from the NTP tries to actually handle the leap second on it's own, when it's been flagged. to do so requires extra code and handling.... and that code had a potential race condition that can cause a freeze-crash in the OS. the thing is... that extra code for handling leap seconds is part of the NTP spec.... you are supposed to do that.... and yet, if the extra code wasn't there on the local side, you'd simply synch up as normal when NTP had a time that's 1 second off. so it turned out that an overthought original solution led to a worse problem than it was supposed to solve. ETA: and that dependency I was wondering about... turns out to be NTP itself =D

07-01-2012, 09:48 PM	#13 (permalink)
Jopsy Pendragon Particle Laboratory Elf Join Date: Nov 2008 Location: Hillcrest, San Diego, USA Posts: 5,549 My Mood: SL Join Date: Jan 15 2004 Business: Light Sorcery	I think the seconds on my clock are accurate... but it's still off a +/- a few week days. Sigh. =) What is today anyway?

07-02-2012, 12:33 AM	#16 (permalink)
Govi feral ballerina Hello, I'm the Groove operator. Please hold the line. Join Date: May 2009 Location: Left coast Posts: 857 My Mood: SL Join Date: March 2004 Business: D3volution	One second sooner than you thought it would, too. That's gonna be a big surprise, come next June.

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