Feature #17513: Methods of shareable objects and UnboundMethods should be shareable

• Status: Assigned
• Assignee: ko1 (Koichi Sasada)
• Target version: -

[marcandre (Marc-Andre Lafortune)]

class Foo
  def foo
  end
end

f = Foo.new.freeze
Ractor.shareable?(f) # => true
Ractor.make_shareable(f.method(:foo).to_proc) # => Proc, ok
Ractor.make_shareable(f.method(:foo)) # => Ractor::Error, expected Method
Ractor.make_shareable(Foo.instance_method(:foo)) # => Ractor::Error, expected UnboundMethod

[Eregon (Benoit Daloze)]

Methods can be defined via define_method { capture_state } and so rely on mutable state, so I guess this is only OK for def methods.

[marcandre (Marc-Andre Lafortune)]

Agreed, some methods can not be made shareable 👍.

[jeremyevans0 (Jeremy Evans)]

• Tracker changed from Bug to Feature
• ruby -v deleted (3.0.0p0)
• Backport deleted (2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN)

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Assigned

[trinistr (Alexander Bulancov)]

A def-ed method of a shareable object may depend on unshareable state. Even worse, shareability of state may dynamically change:

module Checker
  CHECK = []

  def check?
    CHECK.include?(self)
  end
end

class A; include Checker; end

obj = A.new.freeze
Ractor.shareable?(obj) # => true
Ractor.new(obj) { |o| p o.check? } # Ractor::IsolationError

Checker::CHECK.freeze
Ractor.new(A.new.freeze) { |o| p o.check? } # false

Checker::CHECK = []
# And here we go again