Twitter dismisses claims hackers caused two-hour outage

22 Jun 2012

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Twitter has dismissed reports that hackers caused it to go offline at around 9am PDT (5pm GMT) and said the outage was due to a software problem known as a “cascading bug”. Engineering VP Mazen Rawashdeh says it was Twitter itself that “stumbled”.

Yesterday there was stunned disbelief for many Twitter users as the service ground to a halt and many rushed over to Facebook instead to express themselves.

One Twitter user described the two-hour outage as the closest thing to living without oxygen.

In the Twitter blog, Rawashdeh wrote: “At approximately 9am PDT, we discovered that Twitter was inaccessible for all web users, and mobile clients were not showing new tweets. We immediately began to investigate the issue and found that there was a cascading bug in one of our infrastructure components.

Outage not caused by hackers

“This wasn’t due to a hack or our new office or Euro 2012 or GIF avatars, as some have speculated today.

“A ‘cascading bug’ is a bug with an effect that isn’t confined to a particular software element, but rather its effect ‘cascades’ into other elements, as well. One of the characteristics of such a bug is that it can have a significant impact on all users, worldwide, which was the case today. As soon as we discovered it, we took corrective actions, which included rolling back to a previous stable version of Twitter.

“We began recovery at around 10:10am PDT, dropped again around 10:40am PDT, and then began full recovery at 11:08am PDT. We are currently conducting a comprehensive review to ensure that we can avoid this chain of events in the future,” Rawashdeh said.

For many Twitter users, the experience was a reminder of the early days of Twitter when such outages were commonplace and known as fail whales.

Twitter said that over past six months it has enjoyed its highest marks for site reliability and stability ever: at least 99.96pc and often 99.99pc.

This means that in an average 24-hour period, twitter.com has been stable and available to everyone for roughly 23 hours, 59 minutes and 40ish seconds.

“It’s imperative that we remain available around the world, and today we stumbled. For that we offer our most sincere apologies and hope you’ll be able to breathe easier now,” Rawashdeh said.

Editor John Kennedy is an award-winning technology journalist.

editorial@siliconrepublic.com