A leap second sounds harmless until the world’s machines have to live through one. On June 30, 2012, official UTC time briefly displayed 23:59:60, stretching the final minute of the day to keep human clocks aligned with Earth’s uneven rotation. For people, it was a strange timestamp. For servers built around ordinary minutes, sleeping processes, scheduled jobs, and predictable time comparisons, it exposed a fragile assumption hiding deep inside modern infrastructure.
The disruption was not a cinematic internet collapse, but it was unnerving: Reddit became nearly unusable, then went offline, while other services including Mozilla, LinkedIn, Foursquare, Yelp, and Gawker Media reported their own leap-second-related instability. The failures varied across Linux timers, Java systems, Cassandra, Hadoop, Tomcat, and other stacks, but the lesson was shared. Rare code paths are still real code paths, and time — before it becomes a timestamp — is a physical thing that does not always move the way software expects.
Read the original article: https://medium.com/@dia_91230/june-30-23-59-60-the-second-that-made-servers-sweat-d00bc57383eb
Subscribe to The Dead Internet Almanac: https://buttondown.com/dead-internet-almanac