glauber.md Reporter
	Description • 7 years ago

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.86 Safari/537.36 OPR/46.0.2597.26

Steps to reproduce:

1) access website http://www.regexpal.com/
2) enter the following Regular Expression: 
3) enter the folowing Test String: 000.000.000,000,00


Actual results:

The program freeze, I needed to kill the application.


Expected results:

Do not lock up entire browser (?)

	glauber.md Reporter
	Comment 1 • 7 years ago

(In reply to glauber.md from comment #0)
> Created attachment 8882154 [details]
> regexpal_ff54_freeze.PNG
> 
> User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36
> (KHTML, like Gecko) Chrome/59.0.3071.86 Safari/537.36 OPR/46.0.2597.26
> 
> Steps to reproduce:
> 
> 1) access website http://www.regexpal.com/
> 2) enter the following Regular Expression: 
> 3) enter the folowing Test String: 000.000.000,000,00
> 
> 
> Actual results:
> 
> The program freeze, I needed to kill the application.
> 
> 
> Expected results:
> 
> Do not lock up entire browser (?)

The Regular Expression on 'Steps to reproduce - item #2' is: /^([0-9]*\.?[0-9]+)+\,[0-9]+$/

Sorry.

	Ted Campbell [:tcampbell]
	Comment 2 • 7 years ago

This seems to be a slow-script and not a hang (and less problematic now that e10s is on by default). I notice that Chrome also suffers on this case. If I start typing about twenty 0s into the test string, I get slow downs spent in the irregexp library.

Profile: https://perfht.ml/2xar2uQ

The regex itself is quite inefficient as written. Replacing with something like /^(\.?[0-9])+\,[0-9]+$/ does not have any perf problems.

	André Bargull [:anba]
	Comment 3 • 7 years ago

This is similar to bug 1391654 (and there are probably also older bugs for the same issue). The problem can be reduced to `/(a+)+b/.exec("a".repeat(30))`, which will also take its time due to catastrophic backtracking.

	Ted Campbell [:tcampbell]
	Comment 4 • 7 years ago

Thanks André. Let's close this as a duplicate. I like your reduced test case.