End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

class method

Ractor.main

main

# File tmp/rubies/ruby-3.1.3/ractor.rb, line 837
def self.main
  __builtin_cexpr! %q{
    rb_ractor_self(GET_VM()->ractor.main_ractor);
  }
end

returns main ractor

See also .current .make_shareable .count .new also in 4.1 · 4.0 · 3.4 · 3.3 · 3.2 · 3.0