From: eregontp@... Date: 2015-12-30T12:29:13+00:00 Subject: [ruby-core:72619] [Ruby trunk - Misc #11904] Why was Thread.exclusive deprecated? Issue #11904 has been updated by Benoit Daloze. Tony Arcieri wrote: > Is a single-threaded require actually a *guarantee* of every Ruby VM? Not single-threaded, but each file should be loaded at most once. Single require per file/path is certainly highly desirable, otherwise you may load the same file twice. It's also a lot easier to make it thread-safe than autoload IMHO. ---------------------------------------- Misc #11904: Why was Thread.exclusive deprecated? https://bugs.ruby-lang.org/issues/11904#change-55876 * Author: Tony Arcieri * Status: Rejected * Priority: Normal * Assignee: ---------------------------------------- See: https://bugs.ruby-lang.org/projects/ruby-trunk/repository/revisions/52554 Why was Thread.exclusive deprecated? It is useful for when you're uncertain about whether the caller is multithreaded or not, and therefore cannot initialize a mutex because the mutex must be initialized in a thread-safe context where it's not possible for multiple caller threads to initialize the mutex concurrently. One use case is here: this is an idempotent native function invoked via FFI. The contract is that it can be called repeatedly, but only by one thread at a time (concurrent calls from multiple threads can potentially corrupt its internal state): https://github.com/cryptosphere/rbnacl/blob/master/lib/rbnacl.rb#L88 Thread.exclusive is useful because it provides an implicit mutex you can ensure is initialized correctly before any other threads start. -- https://bugs.ruby-lang.org/ Unsubscribe: