Why a mere second has become a real nightmare for the internet giants

Tech giants like Meta, Google, Amazon, and Microsoft have declared war on so-called leap seconds. This insignificant measure of time is used to synchronize the time with variations in rotation of the earth occasionally, but brings down the street of bitterness in the tech industrydestabilizing computers and causing falls suffered by users in Spain and many other countries.

[Gran parte de Internet caída una hora: así ha sido el fallo que ha afectado a Google y otras webs]

Over the years, the internet has become a well-oiled machine that seems to attack everything and everyone, so it might not seem likely that a single second too long can defeat it. Years ago leap seconds or bisiestos they are at the center of a battle between detractors and defenders. It is time to settle this debate.

Representatives from around the world at the World Radiocommunication Conference in Geneva in 2015 disagreed and decided to postpone this resolution to 2023 to get more information. A few months before this date, the most important Internet companies send a clear message, they want to forget this practice and they have the support of French and American institutions.

The leap second

In 1972, the authorities which regulate the measurement of time introduced for the first time a leap second at the standard clock governed by TAI (International Atomic Time). To add that awkward second instead of ending the day from 23:59:59 to 00:00:00, the clock reads 23:59:60.

this trick It has been used up to 27 times since then, being a headache for the many computers that have been created during these decades and on which servers, computer programs and Internet pages depend. When applied, it is announced by the International Earth Rotation and Reference Systems Service and is generally applied on June 31 or December 31, but not every year.

Time on a Mac

Time on a Mac

Damian Patkowski at Unsplash


Proponents of this practice say it remains essential to maintain the link between human timekeeping and the natural cycle of the sun which are intertwined across the planet. It is because the time of rotation of the earth not absolute as clocks are, and the speed at which it rotates depends on different geological events.

the movement of the poles, the production of earthquakes, tsunamis, large air masses or melting ice It affects the speed at which the Earth spins, sometimes speeding up and sometimes slowing down. ANDthen yes, said speed barely at the level of milliseconds.

Earth's rotation

Earth’s rotation

Caleb Woods and Unsplash


Researchers have previously revealed that climate changes and sudden weather events that occur affect the Earth’s axis of rotation. It is very likely that this rotation, in addition to the tilt, will continue to slow down, since since the origin of the planet, the speed of the Earth slowed down about 6 km/h every 10 million yearsmainly due to the gravitational pull produced by the Moon on this planet.

However, the change is so slow that critics of the leap second denounce the fact that the measure remains in force only by tradition and criticize the fact that currently this extra second causes more problems than advantages.

alarm clock on mobile

alarm clock on mobile

Gary Ruiz on Unsplash


In his statement, Meta even considers the headaches it could give a negative leap second, i.e. remove it instead of adding it. A possibility that has been mentioned but which has never been applied. The time jump would look like this from 23:59:58 to 00:00:00. “The impact of a negative leap second has never been tested on a large scale; it could have a devastating effect on software that relies on timers or schedulers,” they explain.

system crash

Those who criticize the use of this extra second list the interruptions that this measure has already caused on the Internet. Meta recalls that the social network Reddit suffered a huge crash in 2012 which blocked users from accessing the platform for 30 or 40 minutes. “The time change disrupted the high-resolution timer (hrtimer), which caused hyperactivity in the servers and blocked the processors of the machines”, they explain.

Also in 2017, Cloudflare saw its DNS (Domain Name System) service which associates the IP addresses of networks on the internet affected. The leap second was the root of the problem which the company itself explained at the time as follows: “The cause of the error that affected our DNS service was the belief that time cannot go back.”

Error 404.

Similar issues have been reported on Mozilla, Linkedin or the airline reservation service. Although bugs or crashes are always fixed in a few hours with the help of the developers in charge of each system, the tech giants are tired of having to put out these fires from time to time and offer alternatives for not using the second again.


“As an industry, we run into problems every time a leap second is introduced,” Complaint Meta insuringor that it “devastates the community every time it happens”. For the company that owns Facebook, Instagram and WhatsApp, the solution is simple: the leap second is a thing of the past and is never used again. For this tech heavyweight just use the TAI system with very stable atomic clocks.

The clock

Ahmad Byagowi, a researcher at this company, assures CNET that using TAI avoids the problem for many years: “We anticipate that if we stick to TAI without observing leap seconds, we should be fine for at least 2,000 years.”

While some offer to touch nothing, others went ahead years ago and devised a mechanism to make the transition even more subtle, using milliseconds. In 2011, Google I already spoke clearly headaches caused by the leap second, when he invented the “leap smear” technique.

[“Nos mataríamos antes de involucionar”: las teorías sobre el apocalipsis de una caída total de Internet]

Instead of adding a whole second to the clock all at once, so you don’t have to audit every line of code that depends on the time, (“That’s a lot of code!” they complained) decided to gradually add a few milliseconds to each update, applying the change smoothly before the end of the day was set.

On December 31, with sweat rolling down their brows, Google engineers were relieved to find that servers were carrying on as normal as they ushered in the new year. “We plan to use this technique again in the future, when new leap seconds are announced by the IERS,” they concluded.

Earth seen from the International Space Station.

Earth seen from the International Space Station.


Another alternative that is gaining strength is that proposed by the International Telecommunications Union. Consists of add one hour to atomic clocks every 600 years to avoid synchronization. But if some prefer to advance the clock, others want to set it back an hour as well, but only when the variation has accumulated a delay of half an hour. Bon University calculated that with this system, an adjustment would not be necessary until the year 2600.

A little less than 5 months from 2023, the technological community must convince a good part of the actors who regulate the weather. The UK was in favor of keeping it the last time they met in Geneva, but the US NIST (National Institute of Standards and Technology) and the French BIPM (Bureau international de Poids et Mesures) are in favor of it. abandonment of the leap second. It may be one less problem, but it’s definitely not the end of server crashes.

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