From: eregontp@... Date: 2021-06-16T09:16:18+00:00 Subject: [ruby-core:104304] [Ruby master Bug#17664] Behavior of sockets changed in Ruby 3.0 to non-blocking Issue #17664 has been updated by Eregon (Benoit Daloze). One potential issue with caching the non-blocking state in Ruby is that a C extension might call fcntl() directly on the fd of an IO to change its non-blocking state. Not sure if that's done in practice, but it could be an issue. ---------------------------------------- Bug #17664: Behavior of sockets changed in Ruby 3.0 to non-blocking https://bugs.ruby-lang.org/issues/17664#change-92526 * Author: ciconia (Sharon Rosner) * Status: Assigned * Priority: Normal * Assignee: ioquatix (Samuel Williams) * ruby -v: 3.0.0 * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN ---------------------------------------- I'm not sure this is a bug, but apparently a change was introduced in Ruby 3.0 that makes sockets non-blocking by default. This change was apparently introduced as part of the work on the [FiberScheduler interface](https://github.com/ruby/ruby/blame/78f188524f551c97b1a7a44ae13514729f1a21c7/ext/socket/init.c#L411-L434). This change of behaviour is not discussed in the Ruby 3.0.0 release notes. This change complicates the implementation of an io_uring-based fiber scheduler, since io_uring SQE's on fd's with `O_NONBLOCK` can return `EAGAIN` just like normal syscalls. Using io_uring with non-blocking fd's defeats the whole purpose of using io_uring in the first place. A workaround I have put in place in the Polyphony [io_uring backend](https://github.com/digital-fabric/polyphony/blob/d3c9cf3ddc1f414387948fa40e5f6a24f68bf045/ext/polyphony/backend_io_uring.c#L28-L47) is to make sure `O_NONBLOCK` is not set before attempting I/O operations on any fd. -- https://bugs.ruby-lang.org/ Unsubscribe: