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perl5411delta.pod - add detail about IsCOW constant-folded strings

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Richard Leach 2024-11-05 00:35:44 +00:00
parent 91e15e585c
commit bddd34c507
1 changed files with 15 additions and 1 deletions
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pod/perl5411delta.pod
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@ -28,7 +28,21 @@ directly>. These cases are now fully supported.
=item *
Various optimizations related to handling of C<CONST>s.
Constant-folded strings are now sharable via the Copy-on-Write mechanism.
[L<GH #22163|https://github.com/Perl/perl5/pull/22163>]
The following code would previously have allocated eleven string buffers,
each containing one million "A"s:
C<my @scalars; push @scalars, ("A" x 1_000_000) for 0..9;>
Now a single buffer is allocated and shared between a CONST OP and
the ten scalar elements of L<@scalars>.
Note that any code using this sort of constant to simulate memory leaks
(perhaps in test files) must now permute the string in order to trigger
a string copy and the allocation of separate buffers. For example,
C<("A" x 1_000_000).time> might be a suitable small change.
=item *