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194 non-PAUSE users
Author image Sawyer X
and 1 contributors


perldelta - what is new for perl v5.25.8


This document describes differences between the 5.25.7 release and the 5.25.8 release.

If you are upgrading from an earlier release such as 5.25.6, first read perl5257delta, which describes differences between 5.25.6 and 5.25.7.

Core Enhancements

New Hash Function For 64-bit Builds

We have switched to a hybrid hash function to better balance performance for short and long keys.

For short keys, 16 bytes and under, we use an optimised variant of One At A Time Hard, and for longer keys we use Siphash 1-3. For very long keys this is a big improvement in performance. For shorter keys there is a modest improvement.

Performance Enhancements

  • New Faster Hash Function on 64 bit builds

    We use a different hash function for short and long keys. This should improve performance and security, especially for long keys.

  • readline is faster

    Reading from a file line-by-line with readline() or <> should now typically be faster due to a better implementation of the code that searches for the next newline character.

Modules and Pragmata

Updated Modules and Pragmata

  • Archive::Tar has been upgraded from version 2.18 to 2.24.

  • B::Debug has been upgraded from version 1.23 to 1.24.

  • bignum has been upgraded from version 0.43_01 to 0.47.

  • Data::Dumper has been upgraded from version 2.165 to 2.166.

  • Encode has been upgraded from version 2.86 to 2.88.

  • encoding has been upgraded from version 2.18 to 2.19.

  • IO has been upgraded from version 1.37 to 1.38.

  • Locale::Codes has been upgraded from version 3.40 to 3.42.

  • Math::BigInt has been upgraded from version 1.999727 to 1.999806.

  • Math::BigInt::FastCalc has been upgraded from version 0.42 to 0.5005.

  • Math::BigRat has been upgraded from version 0.260804 to 0.2611.

  • Module::CoreList has been upgraded from version 5.20161120 to 5.20161220.

  • PerlIO::scalar has been upgraded from version 0.24 to 0.25.

  • Pod::Simple has been upgraded from version 3.32 to 3.35.

  • POSIX has been upgraded from version 1.75 to 1.76.

  • Test::Simple has been upgraded from version 1.302062 to 1.302073.

  • Time::HiRes has been upgraded from version 1.9740_03 to 1.9741.

  • Time::Local has been upgraded from version 1.24 to 1.25.

  • Unicode::Collate has been upgraded from version 1.18 to 1.19.

Configuration and Compilation

  • Zero out the alignment bytes when calculating the bytes for 80-bit NaN and Inf to make builds more reproducible. [perl #130133]

  • Since 5.18 for testing purposes we have included support for building perl with a variety of non-standard, and non-recommended hash functions. Since we do not recommend the use of these functions we have removed them and their corresponding build options. Specifically this includes the following build options:



Perl 5.25.8 represents approximately 4 weeks of development since Perl 5.25.7 and contains approximately 21,000 lines of changes across 500 files from 19 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 18,000 lines of changes to 340 .pm, .t, .c and .h files.

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.25.8:

Andy Lester, Aristotle Pagaltzis, Chad Granum, Chris 'BinGOs' Williams, Christian Hansen, Craig A. Berry, David Mitchell, Hugo van der Sanden, James E Keenan, J. Nick Koston, Karl Williamson, Matthew Horsfall, Niko Tyni, Petr Písař, Sawyer X, Steve Hay, Sullivan Beck, Tony Cook, Yves Orton.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

Reporting Bugs

If you find what you think is a bug, you might check the perl bug database at https://rt.perl.org/ . There may also be information at http://www.perl.org/ , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of perl -V, will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

If the bug you are reporting has security implications which make it inappropriate to send to a publicly archived mailing list, then see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.


The Changes file for an explanation of how to view exhaustive details on what changed.

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.