On the morning of July 1, 2012, significant disruptions took place across multiple sectors as the check-in systems of Qantas and Virgin Australia, along with Reddit, LinkedIn, and Yelp, faced outages. This was attributed to the introduction of a leap second to the global clocks, a process that numerous computer systems found challenging to manage.
### Understanding the Leap Second
The rotation of the Earth is irregular and doesn’t correspond with the accuracy of atomic clocks. Since 1972, timekeepers have been incorporating leap seconds into Coordinated Universal Time (UTC) to align the two. On June 30, 2012, an additional second was included, leading to a 61-second minute at 23:59:60.
### System Failures
One major casualty was Amadeus Altéa, utilized in global aviation reservation systems, which went offline due to a Linux kernel flaw caused by the leap second. Other systems, such as Reddit’s Cassandra database, suffered from excessive processor usage without any output. The primary issue resided in the timer functions of the software, which misfired repeatedly because of unforeseen time modifications, highlighting a defect from 2008 that had not activated until that moment due to the rarity of leap seconds.
### Solutions and Google’s Strategy
Administrators identified a straightforward remedy: resetting their system clocks, which required recalibrating timers. Google sidestepped these issues by employing a “leap smear,” gradually modifying time increments in the hours leading up to the leap second.
### The Future of Leap Seconds
The addition of the leap second encountered difficulties even in 2015, as network connectivity problems emerged. Acknowledging these disruptions, the General Conference on Weights and Measures resolved in 2022 to discontinue leap seconds by 2035 to guarantee consistency and reliability in digital functionalities. Importantly, the potential future requirement may include removing a second if the Earth’s rotational pace accelerates, a situation that has yet to be assessed in current systems.