Another leap second will arrive in June, threatening the stability of UNIX and Linux systems
Robert McMillan / Wired :
Context & Ripple Effects
The 2015 announcement lands on a scarred timeline: when a leap second was last inserted in 2012, it triggered real service outages, and operators spent the run-up to this June inserting fixes — coverage later that year shows companies updating software ahead of the insertion to avoid a repeat. The event is also an early data point in a longer argument: by 2022, [[a:981182|Meta, Google, Microsoft and Amazon had joined NIST's push to scrap the leap second altogether]], precisely because keeping clocks tied to Earth's rotation keeps breaking computer systems.
First-order effects
- UNIX and Linux operators who suffered 2012-style glitches must audit how their systems handle a 23:59:60 second before June, since kernels and applications assuming seconds always count monotonically can hang or crash at insertion.
- Time-sync infrastructure teams at web-scale companies shift from reactive firefighting to pre-deployment patches, making the leap second a scheduled maintenance event rather than a surprise.
Second-order effects
- Vendors of time-distribution software gain a selling point for 'smearing' approaches that spread the extra second across hours, pressuring holdout deployments still syncing strictly to UTC.
- Each outage scare strengthens the cloud giants' hand with standards bodies like NIST, turning a niche horological convention into a lobbying target for the companies whose fleets absorb the risk.
Third-order effects
- If the pattern holds, civil timekeeping decouples from astronomical time entirely — a structural split between Earth-referenced UTC and the smoothed internal clocks of large computing platforms, with regulators eventually forced to pick a side.
- Recurring clock-edge failures (leap seconds, Y2038-style limits) harden the norm that kernel time handling is a security-and-reliability surface requiring the same patch discipline as vulnerabilities like the Ghost bug Linux makers rushed to fix the same month.
The trend: Computer operators are steadily pushing to replace astronomically derived time corrections like the leap second with engineered, platform-controlled timescales.