From: eregontp@... Date: 2021-02-16T23:33:41+00:00 Subject: [ruby-core:102548] [Ruby master Feature#17592] Ractor should allowing reading shareable class instance variables Issue #17592 has been updated by Eregon (Benoit Daloze). I should add, instance variable writes on modules on TruffleRuby are already synchronized (for modules assigned to a constant, and effectively reachable by multiple threads), and that doesn't seem to be a performance issue at all. Reading can be done without synchronization for existing variables (just need to check if the ivar storage is large enough if it's only growing). ---------------------------------------- Feature #17592: Ractor should allowing reading shareable class instance variables https://bugs.ruby-lang.org/issues/17592#change-90450 * 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: