On: Details of the Cloudflare outage on July 2, 2019

[isaacg]

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 → isaacg]

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.