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=item ${^RE_SUPERLINEAR_CACHE_DELAY}

Added in Perl 5.46.0.

This integer-valued variable allows the initial countdown delay in the
regex engine's super-linear cache mechanism to be adjusted for testing and
debugging purposes. It is not intended for production code, and its
semantics may change without notice.

When matching a complex pattern with much backtracking, after a certain
number of iterations a cache is allocated to detect backtracks to the same
position and state. The countdown is intended so that the cache isn't
wastefully allocated for every match, but instead only for matches which
seem to be backtracking too much. Normally the initial countdown is
proportional to the length of the string being matched.

This variable's value has the following meanings:

=over

=item 0

Use the default delay countdown value.

=item 1+

Use the specified number of countdown iterations (1 implies no delay).

=item -1

Disable the cache completely.

=item -N (other than -1)

Scale the normal delay count by C<N / 1E6> (so for example -500000 causes
half as many countdown iterations as normal).

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