Linux is culprit in leap-second lapses: Cassandra exec

The Linux kernel has a bug in how it handles leap seconds, according to the creator of the Cassandra database

A number of high-profile outages that took place last weekend can be traced back to how the Linux OS kernel mishandled a leap second added to the official time, charges the CTO of DataStax, a company that manages the open source Cassandra database.

"Initial reporting often fingered Java or even Cassandra as the culprit ... but the actual problem was a kind of livelock in the Linux system calls responsible for timers," wrote DataStax CTO and Cassandra creator Jonathan Ellis, in a blog post.

On Saturday midnight Greenwich Mean Time (GMT), an extra second was added to the Universal Coordinated Time (UTC), the official time used to coordinate servers across the Internet. Although the Network Time Protocol (NTP), the most widely used mechanism to synchronize the time across the Internet, was designed to handle leap seconds, a number of popular Internet services briefly went offline after the second was inserted in their servers, including those running Reddit, LinkedIn and the Quantas airline reservation system.

ReddIt engineers had initially assumed that Cassandra, along with Java, was source of its leap- second related outage on Saturday. The problem wasn't with either of those technologies, Ellis countered, but rather with the underlying OS. (Oracle, which manages Java, did not immediately respond to comment).

A system administrator would have first noticed the problem manifesting as an extremely high system load or even a system crash that could be traced back, via the normal administrative tools, to an application such as Cassandra, the Java Virtual Machine, Hadoop, or MySQL. The actual culprit, however, turned out to be a harder-to-pinpoint bug in the way Linux updated its clocks when a leap second was introduced, Ellis said.

Many had found that resetting the application did not restore the server to normal operation. They could, however, remedy the issue by resetting the system clock or rebooting the server.

Whatever the cause, the bug disrupted the Saturday evenings of many a system administrator. On the Time-Nuts mailing list, one admin reported spending the evening rebooting hundreds of servers.

Joab Jackson covers enterprise software and general technology breaking news for The IDG News Service. Follow Joab on Twitter at @Joab_Jackson. Joab's e-mail address is Joab_Jackson@idg.com

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Joab Jackson

IDG News Service
Show Comments

Father’s Day Gift Guide

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?