Issue #17678 has been updated by jeremyevans0 (Jeremy Evans). Tracker changed from Bug to Feature ruby -v deleted (ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-linux]) Backport deleted (2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN) As Ractors always use separate OS threads, and fork only runs the current thread in the forked process, I don't see a way for Ractors to continue where they left off after fork. I think auto-starting would likely be a bad idea, because auto-starting would not return them to the state they were at fork. The addition of `Ractor#alive?` and/or `Ractor#status` makes sense to me. Even in non-forked processes such methods could be useful. Note that you can get what you want already, by calling `Ractor#inspect`, so these methods would only need to expose information that Ractor is already storing. ---------------------------------------- Feature #17678: Ractors do not restart after fork https://bugs.ruby-lang.org/issues/17678#change-104304 * Author: ivoanjo (Ivo Anjo) * Status: Assigned * Priority: Normal * Assignee: ko1 (Koichi Sasada) ---------------------------------------- Hello there! I'm working at Datadog on the `ddtrace` gem -- <https://github.com/DataDog/dd-trace-rb> and we're experimenting with using Ractors in our library but run into a few issues. ### Background When running a Ractor as a background process, the Ractor stops & does not restart when the application forks. ### How to reproduce (Ruby version & script) `ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-linux]` ```ruby r2 = Ractor.new do loop { puts "[#{Process.pid}] Ractor"; sleep(1) } end sleep(1) puts "[#{Process.pid}] Forking..." fork do sleep(5) puts "[#{Process.pid}] End fork." end loop do sleep(1) end ``` ### Expectation and result The application prints “Ractor” each second in the main process, but not in the fork. Expected the Ractor (defined as `r2`) to run in the fork. ``` [29] Ractor [29] Ractor [29] Forking... [29] Ractor [29] Ractor [29] Ractor [29] Ractor [29] Ractor [32] End fork. [29] Ractor [29] Ractor [29] Ractor ``` ### Additional notes Threads do not restart across forks either, so it might not be unreasonable to expect consistent behavior. However, it’s possible to detect a dead Thread and recreate it after a fork (e.g. with `#alive?`, `#status`), but there’s no such mechanism for Ractors. ### Suggested solutions 1. Auto-restart Ractors after fork 2. Add additional methods to Ractors that allow users to check & manage the status of the Ractor, similar to Thread. -- https://bugs.ruby-lang.org/