Issue #20877 has been reported by ioquatix (Samuel Williams). ---------------------------------------- Bug #20877: Introduce (public) debug assertion for holding the GVL. https://bugs.ruby-lang.org/issues/20877 * Author: ioquatix (Samuel Williams) * Status: Open * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- I found issues with `zlib.c` calling `rb_` functions without holding the GVL: https://bugs.ruby-lang.org/issues/20863 ## Background The GVL must be held before many of Ruby's C functions can be called. However, few functions enforce this. Even thought it may work in many scenarios, it may break unexpectedly (SEGFAULT etc). ## Proposal I think we should (1) add more debug checks within CRuby for detecting this invalid usage and (2) expose a public macro that can be used by Ruby's native extensions so that they may do the same. The current internal implementation looks like this: ```c RUBY_ASSERT(ruby_thread_has_gvl_p()); ``` While fixing `zlib.c`, I made a simple PR to demonstrate the change: https://github.com/ruby/ruby/pull/11975 `ruby_thread_has_gvl_p` is not a public interface at this time, so we can't use it in native extensions. I would like to consider adding a public macro to allow for this, e.g. `RUBY_DEBUG_ASSERT_GVL` or something similar. Finally, I propose to add this macro to all methods that should be executed with the GVL so that we catch invalid usage. If the name `RUBY_DEBUG_ASSERT_GVL` is not suitable / too specific, maybe some other ideas: - `RUBY_DEBUG_ASSERT_THREAD` - `RUBY_DEBUG_ASSERT_CURRENT_THREAD` or `RUBY_DEBUG_ASSERT_CURRENT_THREAD_P` - `RUBY_DEBUG_ASSERT_GVL` or `RUBY_DEBUG_ASSERT_GVL_P` - `RUBY_DEBUG_ASSERT_INTERPRETER_LOCKED` I don't have a strong opinion on naming, but I have a strong opinion about preventing invalid usage. -- https://bugs.ruby-lang.org/