Ruby 2.4.0-preview2 Released

We are pleased to announce the release of Ruby 2.4.0-preview2.

Ruby 2.4.0-preview2 is the second preview of Ruby 2.4.0. This preview2 is released to get feedback from the community. Feel free to send feedback since you can still influence the features.

Unify Fixnum and Bignum into Integer

Though ISO/IEC 30170:2012 doesn’t specify details of the Integer class, Ruby had two visible Integer classes: Fixnum and Bignum. Ruby 2.4 unifies them into Integer. All C extensions which touch the Fixnum or Bignum class need to be fixed.

See also the ticket and akr’s slides.

String supports Unicode case mappings

String/Symbol#upcase/downcase/swapcase/capitalize(!) now handle Unicode case mappings instead of only ASCII case mappings.

Performance improvements

Ruby 2.4 also contains the following performance improvements including language changes:

Array#max, Array#min

[x, y].max and [x, y].min are optimized to not create a temporary array under certain conditions.


Added Regexp#match?, which executes a regexp match without creating a back reference object and changing $~ to reduce object allocation.

Other performance improvements


Thread#report_on_exception and Thread.report_on_exception

Ruby ignores exceptions in threads unless another thread explicitly joins them. With report_on_exception = true, you can notice if a thread has died due to an unhandled exception.

Send us feedback what should be the default for report_on_exception and about report-on-GC, which shows a report when a thread is garbage collected without join.

Thread deadlock detection now shows threads with their backtrace and dependency

Ruby has deadlock detection around waiting threads, but its report doesn’t include enough information for debugging. Ruby 2.4’s deadlock detection shows threads with their backtrace and dependent threads.

Try and enjoy programming with Ruby 2.4.0-preview2, and send us feedback!

Other notable changes since 2.3

  • Support OpenSSL 1.1.0
  • ext/tk is now removed from stdlib Feature #8539

See NEWS and ChangeLog for details.

With those changes, 2353 files changed, 289057 insertions(+), 73847 deletions(-) since Ruby 2.3.0!



    • SIZE: 12463225 bytes
    • SHA1: 95a501624f1cf4bb0785d3e17afd0ad099f66385
    • SHA256: 2224c55b2d87b5c0f08d23a4618e870027dbc1cffbfb4a05efd19eac4ff4cf1d
    • SHA512: 0c9a59a2f57a99c4ee8539a30f41da1de7547566203f89d856e1be9dbb44365754e6c470145dc9336eb324e0feb2f53d9fef18a1564968ac21f9ee528905949f

    • SIZE: 15586514 bytes
    • SHA1: 492a13c4ddc1c0c218433acb00dcf7ddeef96fe0
    • SHA256: fec544836428aada2dc593a8cc42ce330798a805e49ecb807a0e21b386fd0b14
    • SHA512: 5a3de852a7611e79f38219ed7bb13772aaabb25538ca843d38743180a0cc939a4e34c008b61d578da785285196b6b8882270bddc17cbed481237db8afa4c54e4

    • SIZE: 9886832 bytes
    • SHA1: 95d5fd7d54d86497194f69ec433755a517dcde8f
    • SHA256: 6c2d25bedc50c2f19b0e349f0ffd9b9a83000d9cb6a677bf5372fb493d33e16a
    • SHA512: b9bd898d17583103ee61b4764ac86eb62c9661fca1f41ff0d06a15965a0a1ba581491d4b8a342e527d63e102b6ddcb2acebdabe5b246409ce9711e13f9428d5b

    • SIZE: 17401564 bytes
    • SHA1: 5f3a5b2fd03f70d49e74ec36be3e0c110f6c17cc
    • SHA256: 4d0e466148283ad52208b1e1b70b018aefb7fa95b490fc862d5ea4ca284ecdd2
    • SHA512: 0ef2098d995238580245a4bcee843641199c1194189be13614611e2ffec329278072319a799d409eaf13b1cff45f05a0eae02d9ea8ccc69058fa49e03eca0130

Release Comment

See also the release schedule and other information: