Ruby 2.4.0-rc1 Released

We are pleased to announce the release of Ruby 2.4.0-rc1.

Ruby 2.4.0-rc1 is the first release candidate of Ruby 2.4.0. This rc1 is released to get feedback from the community. Feel free to send feedback since you can still fix the features.

Introduce hash table improvement (by Vladimir Makarov)

Improve the internal structure of hash table (st_table) by introducing open addressing and an inclusion order array. This improvement has been discussed with many people, especially with Yura Sokolov.

Binding#irb: Start a REPL session similar to binding.pry

While you are debugging, you may often use p to see the value of variables. With pry you can use binding.pry in your application to launch a REPL and run any Ruby code. r56624 introduces binding.irb which behaves like that with irb.

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-rc1, and send us feedback!

Other notable changes since 2.3

  • Support OpenSSL 1.1.0 (drop support for 0.9.7 or prior)
  • ext/tk is now removed from stdlib Feature #8539
  • XMLRPC is now removed from stdlib Feature #12160

See NEWS or commit logs for details.

With those changes, 2519 files changed, 288606 insertions(+), 83896 deletions(-) since Ruby 2.3.0!



    SIZE:   12512729 bytes
    SHA1:   a0439652a97a2406b691e8a1e586e2cf08c258ba
    SHA256: 3b156b20f9df0dd62cbeeb8e57e66ea872d2a5b55fabdef1889650122bcc2ea7
    SHA512: b43902ac7794487197df55a45256819d2e7540b77f1ed4eb68def3e0473ee98860a400862075bafadbde74f242e1dfe36a18cd6fe05ac42aae1ea6dddc9978ce

    SIZE:   14098505 bytes
    SHA1:   6b242f9ec7b908c9aa26e497440684ba06d86927
    SHA256: e41ada7650eed2a5800534d1201ba7c88f1627085659df994f47ab4c5e327745
    SHA512: 26d3c60483ce2d6eaabd7077085102fad6633f18cf5d772bacf6f563670030cb7bba22d54d8b7dfa5eac8b52990371c4a6ad1c095dff6f6b3a7bbe1a8ffb3754

    SIZE:   9930088 bytes
    SHA1:   7c404e8bec9859f708927f7203d4f42187e678b7
    SHA256: 3f014b3186d10676da6c512d14c65db23ccc4bf200fed9d7c6f9a58fd1e3295b
    SHA512: 22e209e28da1f2394f50c0a7dd5d0d4d4c0c5a6b5b0b02260fad0267a0940b98f0e2b0f36a44f87d1612555cb3022f43cd136a5186c7f87650aa20264408d415

    SIZE:   15785968 bytes
    SHA1:   7d82386434ccbb1701f2995286bf29c8b9179e01
    SHA256: 14e6910e36618cddffeb22bad5f1052f907dc31ec93d4aa945bca0905d8a52c4
    SHA512: 5dd89320d429e5bd5faf3709be7e5b70f7355304d6324d7ac13a69187e5f1446ad5988c8186bc33f4fea8934288294f9d16fea173f39b2b39967746c4b03d1d4

Release Comment

See also the release schedule and other information: