php regular length limit

Scenario: When using regular expressions to match page content (preg_match('/(.*)(.*)(.*)/Uis',$str)), it is found that sometimes Normal matching, sometimes not, you can analyze the page structure and find that there is no change, the only change is the page size.

Reason: PHP limits the matching length of regular expressions. You can see the following with phpinfo

pcre.backtrack_limit 100000 100000
pcre.recursion_limit 100000 100000

I found that there is only 100K, which is definitely not enough if you are grabbing a web page. , in fact, just make the corresponding settings on php.ini (or change the size of these two values)

pcre.backtrack_limit=-1
pcre.recursion_limit=-1

Attached note:

[Pcre]
; Perl compatible regular expression module
pcre.backtrack_limit = 100000
; The maximum number of backtracking steps for PCRE.
pcre.recursion_limit = 100000
; The maximum recursion depth of PCRE.
; If you set this value very high, you may run out of process stack space and cause PHP to crash.