From: marcandre-ruby-core@... Date: 2020-12-27T17:30:22+00:00 Subject: [ruby-core:101752] [Ruby master Bug#17420] Unsafe mutation of $" when doing non-RubyGems require in Ractor Issue #17420 has been updated by marcandre (Marc-Andre Lafortune). Maybe a solution would be to do all `require` in the main Ractor? Something like whenever a new Ractor is created, the main thread could spin a private thread to do the needed `require`. When a `require` call happens, or a constant needs to be autoloaded, from within a Ractor other than main, inter-Ractor communication could be used (special tag to insure proper communication) to do the loading in the main thread. ---------------------------------------- Bug #17420: Unsafe mutation of $" when doing non-RubyGems require in Ractor https://bugs.ruby-lang.org/issues/17420#change-89579 * Author: Eregon (Benoit Daloze) * Status: Open * Priority: Normal * Assignee: ko1 (Koichi Sasada) * ruby -v: ruby 3.0.0dev (2020-12-16T10:12:48Z master a9a7f4d8b8) [x86_64-linux] * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- With an empty file `a.rb`: ``` $ ruby --disable-gems -e 'Ractor.new { puts $" }.take' -e:1:in `block in
': can not access global variables $" from non-main Ractors (RuntimeError) ``` That is expected, given the rules for global variables. ``` ruby --disable-gems -e 'Ractor.new { require "./a.rb"; }.take; p $"' [... , "/home/eregon/a.rb"] ``` Is it OK that the Ractor can do `require`, which does modify `$"`? I think it's not, and it might lead to segfaults if e.g. the main Ractor mutates `$"` in parallel to some other Ractor doing `require`. Probably `require` needs to be forbidden in non-main Ractors (it does mutate `$"`, so it's logical), or there needs to be always VM-global synchronization on any access to `$"` (otherwise, segfaults are possible). The latter doesn't seem reasonable, especially when considering the user might do `$".each { ... }`. --- Note that RubyGems' `require` does not work on non-main Ractors (pretty much expected given it depends on a lot of global state): ``` $ ruby -e 'Ractor.new { require "./a.rb"; }.take' :37:in `require': can not access non-shareable objects in constant Kernel::RUBYGEMS_ACTIVATION_MONITOR by non-main ractor. (NameError) ``` This probably also has consequences for `autoload`. Maybe the `zeitwerk` gem can help with the mode to resolve all autoload at once. -- https://bugs.ruby-lang.org/ Unsubscribe: