From: marcandre-ruby-core@... Date: 2021-01-29T17:03:16+00:00 Subject: [ruby-core:102308] [Ruby master Feature#17592] Ractor should allowing reading shareable class instance variables Issue #17592 has been updated by marcandre (Marc-Andre Lafortune). From a discussion with @ko1, config could be (or should be?) using `TVar`. We need a good solution that is builtin. If `TVar` becomes builtin, then that is a possible solution. It seems like overkill for a mostly constant config (e.g. URI scheme list) and is not backwards compatible though. Allowing `reading` from instance variables has the advantage of being simple and backward compatible. Just to be clear: `TVar` seems like interesting addition, but not particularly for config-style global state. ---------------------------------------- Feature #17592: Ractor should allowing reading shareable class instance variables https://bugs.ruby-lang.org/issues/17592#change-90165 * 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: