How Facebook Keeps Messenger From Crashing On New Year's Eve

Wave723 quotes IEEE Spectrum: On New Year's Eve, millions of people will use Facebook's Messenger app to wish friends and family a 'Happy New Year!' If everything goes smoothly, those messages will reach recipients in fewer than 100 milliseconds, and life will go on. But if the service stalls or fails, a small team of software engineers based in the company's New York City office will have to answer for it.

The article says the team 'tested and tweaked the app throughout the year and will soon face their biggest annual performance exam,' since Messenger's 1.3 billion monthly active users send more messages on New Year's Eve than any other day of the year. Many of them hit 'send' at the exact moment when their clock strikes midnight, 'and people often try to resend messages that don't appear to make it through right away, which piles on more requests.'

The solution appears to be load testing, re-directing traffic, message batching, and discarding 'read receipts' and temporarily disabling other minor Facebook functions -- or, more generally, what their engineering manager describes as 'graceful degradation.'

Read more of this story at Slashdot.