5 ms·

StackOverflow also had an outage a few years ago that was caused by exponential blow-up of a backtracking regular expression. https://stackstatus.net/post/1477

• isaacg 7y ago
  That blow up is quadratic, not exponential: "This is not classic catastrophic backtracking (talk on backtracking) (performance is O(n²), not exponential, in length), but it was enough."
  • perlgeek 7y ago
    Some years ago I tried to create an exponential time regex in Perl, and only managed a quadratic time one after a bit of experimenting. But, as you said, quadratic is often already fatal on realistic data.