Twitter went down between about 8:20 a.m. and 9 a.m. Pacific Time on Thursday and was by about 10:25 a.m., wrote Mazen Rawashdeh, vice president of engineering. Though some users suspected an overload of Tweets related to the Olympic Games, which opens on Friday in London, that was not the cause of the outage.

Instead, two data centers that operate in parallel for redundancy both failed, in what Rawashdeh called an "infrastructural double whammy."

"What was noteworthy about today's outage was the coincidental failure of two parallel systems at nearly the same time," Rawashdeh wrote. "We are investing aggressively in our systems to avoid this situation in the future."

It was Twitter's second outage in about six weeks. On June 21, the microblogging service about 9 a.m. Pacific and started to come back just after 10 a.m., only to fail again before full recovery began after 11 a.m. The company that outage on a cascading bug, a type of problem that spreads from one software element to others.

The IDG News Service