Limits the complexity of regex searches. If a regex search passes the
specified complexity limit without either finding a match or determining
that no match exists, it bails out, throwing an exception (see
CompiledRegex.match()).
The default value of 0 uses libpcre's built-in default complexity
limit (10 million, see below), which is set to be extremely permissive.
Any value less than 10 million will have the effect of reducing the
level of complexity tolerated, thus reducing the potential processing
time spent searching.
This field maps directly to the match_limit field in libpcre's
pcre_extra struct.
The match_limit field provides a means of preventing PCRE from using up
a vast amount of resources when running patterns that are not going to
match, but which have a very large number of possibilities in their
search trees. The classic example is the use of nested unlimited
repeats.
Internally, PCRE uses a function called match() which it calls
repeatedly (sometimes recursively). The limit set by match_limit is
imposed on the number of times this function is called during a match,
which has the effect of limiting the amount of backtracking that can
take place. For patterns that are not anchored, the count restarts from
zero for each position in the subject string.
The default value for the limit can be set when PCRE is built; the
default default is 10 million, which handles all but the most extreme
cases.
Limits the complexity of regex searches. If a regex search passes the specified complexity limit without either finding a match or determining that no match exists, it bails out, throwing an exception (see CompiledRegex.match()).
The default value of 0 uses libpcre's built-in default complexity limit (10 million, see below), which is set to be extremely permissive. Any value less than 10 million will have the effect of reducing the level of complexity tolerated, thus reducing the potential processing time spent searching.
This field maps directly to the match_limit field in libpcre's pcre_extra struct.
From http://regexkit.sourceforge.net/Documentation/pcre/pcreapi.html:
The match_limit field provides a means of preventing PCRE from using up a vast amount of resources when running patterns that are not going to match, but which have a very large number of possibilities in their search trees. The classic example is the use of nested unlimited repeats.
Internally, PCRE uses a function called match() which it calls repeatedly (sometimes recursively). The limit set by match_limit is imposed on the number of times this function is called during a match, which has the effect of limiting the amount of backtracking that can take place. For patterns that are not anchored, the count restarts from zero for each position in the subject string.
The default value for the limit can be set when PCRE is built; the default default is 10 million, which handles all but the most extreme cases.