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The Leap Second Is Here! Are Your Systems Ready?
Tmack writes "The last time we had a leap second, sysadmins were taken a bit by surprise when a random smattering of systems locked up (including Slashdot itself) due to a kernel bug causing a race condition specific to the way leap seconds are handled/notified by ntp. The vulnerable kernel versions (prior to 2.6.29) are still common amongst older versions of popular distributions (Debian Lenny, RHEL/CentOS 5) and embedded/black-box style appliances (Switches, load balancers, spam filters/email gateways, NAS devices, etc). Several vendors have released patches and bulletins about the possibility of a repeat of last time. Are you/your team/company ready? Are you upgraded, or are you going to bypass this by simply turning off NTP for the weekend?"
Update: 07/01 03:14 GMT by S : ZeroPaid reports that this issue took down the Pirate Bay for a few hours.
Leap years = no problem.
Leap seconds = kernel panic.
I fear for teh internets if we try a leap millisecond.
I can see the fnords!
When NTP tries to say that it is 12:34:61 and the computer only expects 1-60.
For those wondering whether they get one more second of sleep tonight or one less, the rule is 'spring forwards, fall back, summer stand there looking confused'.
It actually goes 23h 59m 59s, 23h 59m 60s, 00h 00m 00s. See http://www.nist.gov/pml/div688/leapseconds.cfm
Poorly written software only expects seconds to go from 0-59. Positive leap seconds are counted 23:59:59 -> 23:59:60 -> 0:0:0. Leap seconds have been around since 1972, the same year Unix was rewritten in C. There's been plenty of time to get things right.
"National Security is the chief cause of national insecurity." - Celine's First Law
Enjoy your free operating system that was stopped by an extra second.
Yes, because we've NEVER seen Windows have problems dealing with things like Daylight Savings...
#DeleteChrome
Hello, Some of us code our systems somewhat like a finite state machine, and we figure our machine will never operate outside it.
,Jim
If you're testing if something that increments ever hits a number(like 10) and goes back to 0, instead of checking if it ==10, check if it is >9.
There are a lot of defensive coding mechanisms you can use. The downside of this is that when you debug, something can sneak by and put you outside of a state you want, so it makes it ever so slightly harder to debug. But if you're making software that will be used by the public that is hard to give updates, defensive programming can save the day here and there.
God spoke to me
Because that would be the opposite of a leap second maybe?
What a fool believes, he sees, no wise man has the power to reason away.
Our servers run on octal, you insensitive clod.
Yeah it had the wrong time but did not freeze up. What's your excuse?
You're really trying that hard to troll huh?
A free operating system has a bug in it so you want to exaggerate the existence of the bug to show that free operating systems are inferior in such a condescending and acerbic way.
I guess that can work. It's not like there is any paid OS out there that has decades long histories of serious instability, security flaws, and badly implemented ideas...... so yeah, you're completely safe making such an arrogant argument.
Windows: 95. Scene: LAN party. Game: Descent. Hilarity: All the Windows users cursing loudly as their computers spontaneously reboot for DST. DOS users get to feel smug for a change.
Windows has been boning DST as long as Windows has handled your RTC.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Looks like Reddit's systems weren't ready for the leap second. It been down since around midnight (UTC). You'd think a site as big as that would be ready for such an event.
And which parallel universe did you crawl out of?
All my Java processes peg the CPU since the leap second, even if I restart them. Maybe a reboot will help...
So just like before, then?
Normally java is just in "waste memory" mode. Now it's "waste memory AND CPU".
Why would a Unix application ever see the :60? Any time someone checks the clock, the time should be derived from Unix time (seconds since the epoch) which doesn't account for leap seconds. So to an application it should appear as a duplicate :00 or :59.
https://twitter.com/redditstatus/status/219244389044731904 just said so -- "We are having some Java/Cassandra issues related to the leap second at 5pm PST. We're working as quickly as we can to restore service." :D
Ant(Dude) @ Quality Foraged Links (AQFL.net) & The Ant Farm (antfarm.ma.cx / antfarm.home.dhs.org).
Unfortunately some GPS vendors don't get it right. I was testing conformance of a IT530 from FastRaxGPS which uses the Mediatek MT3339 receiver.
It put out the sequence 23:59:59, 23:59:59, 00:00:00 repeating second 59 instead of using second 60.
/etc/init.d/ntpd stop; date; date `date +"%m%d%H%M%C%y.%S"`; date;
Fixed the issues I was having. Credit goes to https://twitter.com/SilvioSantoZ/status/219250677522767872. I didn't have to restart anything after running it. YMMV
When NTP tries to say that it is 12:34:61 and the computer only expects 1-60.
That will never happen.
Leap seconds are always asserted at UTC midnight on the last day of a month. I think the convention is only to have leap second opportunities at the end of March, June, September and December. Typically, they try to assert it at midnight December 31. It's unusual to have a mid-year leap-second.
Since the normal progression is 23:59:58, 23:59:59, 00:00:00, the extra second makes the time 23:59:60. 61 would be TWO leap seconds which won't happen any time soon. The Earth's rate of rotation would have to change by nearly two seconds in 3 months.
anything that runs its kernel on GPS time can give correct UTC time by following this prescription http://www.ucolick.org/~sla/leapsecs/right+gps.html
What the heck is the opposite of a leap second?
A leap anti-second?
A day is one Earth revolution, relative to Sol. It varies slightly because of a number of factors, and is called UT1. UT2R is a smoothed version, and but variations due to unpredictable events are left. UTC is based on the atomic second. The value chosen for the atomic second is such that, on average, there have been slightly more than 86400 of them in a day. So, just as a year is more than 365 days (a day is slightly shorter than 1/365 year), so an occasional leap day needs to be added, so to an occasional leap second is needed.
Contrary to what the GP said, the solar day is not too fast. It is what it is, by definition. Rather, the second is a bit too short.
On average, since the leap second was introduced in 1972, one has been needed about every 18 months. Over the long term, that rate will increase as tidal acceleration slows the earth. 1 sec/18 months ~= 2e-8, so that's how much the second has been off on average since 1972. The atomic value for the second is 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. So, a better value might have been 9,192,631,967, which would make us about even to date. (Although, since leap seconds aren't distributed evenly, they would still have occurred, both positive and negative, just not as many.) The original value was based on measurements made over less than 3 years, and has worked for some shorter periods (there were no leap seconds between 1999 and 2004, for example), but the value chosen has proven to be too short over the 40 years of leap seconds.
"National Security is the chief cause of national insecurity." - Celine's First Law
The issue is that a lot of software was written on the assumption that there are 60 seconds in a minute. If something happens at the 61st second of a minute, stuff gets confused. Either it rejects the event, or incorrectly marks the time. Leap seconds are an incredibly expensive idiocy designed to make a few astronomers happy.
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