From: shyouhei@... Date: 2016-11-25T03:41:32+00:00 Subject: [ruby-core:78298] [Ruby trunk Misc#11904] Why was Thread.exclusive deprecated? Issue #11904 has been updated by Shyouhei Urabe. I feel that Thread.exclusive is too big a primitive to merely initialize a mutex at a process startup. We could perhaps introduce pthread_once_t analogous more fine-grained light-weight control structure that does the job. P.S. we have /#{@mutex=Mutex.new}/o, so we already have such thing, to some extent at least. ---------------------------------------- Misc #11904: Why was Thread.exclusive deprecated? https://bugs.ruby-lang.org/issues/11904#change-61660 * 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: