Is there a known input length limitation with the Regex module (or I assume probably :re under the covers)?

I just spent a while debugging some code that generally worked, but was failing to match for certain inputs which seemed valid. Eventually I narrowed it down to the sheer size of the strings where it failed.

Here’s a simplified example. This works:

text = "START\n" <> Enum.map_join(1..100_000, "\n", &"Line #{&1}") <> "\nEND\n"
Regex.run(~r/START(.*?)END/ms, text)
# => ["START\nLine 1\nLine 2\nLine 3\nLine 4\nLine 5\n\n" <> ...]

But if I increase the number of lines by another order of magnitude, the same pattern stops matching:

text = "START\n" <> Enum.map_join(1..1_000_000, "\n", &"Line #{&1}") <> "\nEND\n"
Regex.run(~r/START(.*?)END/ms, text)
# => nil

No doubt this is a terrible regex, and I can imagine it having performance implications, but I was a bit surprised that it silently failed, indicating no matches, rather than raising an exception.