From: daniel@...42.com Date: 2021-02-01T16:58:12+00:00 Subject: [ruby-core:102363] [Ruby master Feature#17592] Ractor should allowing reading shareable class instance variables Issue #17592 has been updated by Dan0042 (Daniel DeLorme). If a class instance variable refers to a shareable object it would make sense to be able to read it in ractors. But what about reassigning the instance variable? How does the proposal work then? ```ruby ## in main ractor: @a = Ractor.make_shareable(data) # @a is readable in ractors @a = data # @a is no longer readable in ractors? assignment disallowed? ## in non-main ractor: @a = Ractor.make_shareable(data) # ??? ``` ---------------------------------------- Feature #17592: Ractor should allowing reading shareable class instance variables https://bugs.ruby-lang.org/issues/17592#change-90224 * Author: marcandre (Marc-Andre Lafortune) * Status: Open * Priority: Normal * Assignee: ko1 (Koichi Sasada) ---------------------------------------- It would be very helpful if Ractor was allowing reading class instance variables from non-main Ractor. Currently is raises an IsolationError: ```ruby module Foo singleton_class.attr_accessor :config Foo.config = {example: 42}.freeze end Ractor.new { p Foo.config } # => IsolationError ``` This limitation makes it challenging to have an efficient way to store general configs, i.e. global data that mutated a few times when resources get loaded but it immutable afterwards, and needs to be read all the time. Currently the only way to do this is to use a constant and use `remove_const` + `const_set` (which can not be made atomic easily). I think that allowing reading only may be the best solution to avoid any race condition, e.g. two different Ractors that call `@counter += 1`. The only 3 scenarios I see here are: 0) declare the constant hack the official way to store config-style data 1) allow reading of instance variables for shareable objects (as long as the data is shareable) 2) allow read-write I prefer 1) -- https://bugs.ruby-lang.org/ Unsubscribe: