Issue #20272 has been updated by luke-gru (Luke Gruber). The messages in that case would be guaranteed to be received in order (first "hello" then "world"). If you have 2 different ractors or 2 different threads both receiving messages from the same ractor, then there is no guarantee of the order. ---------------------------------------- Misc #20272: Ambiguity around Ractor message sending FIFO semantics https://bugs.ruby-lang.org/issues/20272#change-108137 * Author: forthoney (Seong-Heon Jung) * Status: Open ---------------------------------------- The docs should explicitly state the semantics/properties of Ractor message, especially when it comes to FIFO. For example, assume I have two Ractors, Ractor A and Ractor B. Ractor A sends two messages `"hello"` and `"world"` in this order to Ractor B. If I call `Ractor.receive` on Ractor B, am I guaranteed to see `"hello"` and then `"world"` or is it possible the messages are delivered out of order? -- https://bugs.ruby-lang.org/